Oil sand processing apparatus control system and method

ABSTRACT

A control system for an oil sand processing apparatus and a method for controlling the apparatus. The apparatus includes a rotatable drum, an oil sand feed mechanism, a drive mechanism for rotating the drum, a first drum support and a second drum support. The control system includes a first drum load sensor associated with the first drum support for sensing a first drum load, a second drum load sensor associated with the second drum support for sensing a second drum load and an oil sand feedrate sensor associated with the oil sand feed mechanism for sensing a feedrate of the oil sand feed mechanism. A controller is provided for controlling a rotation speed of the drum and a feedrate of the oil sand feed mechanism in response to input data from the first drum load sensor, the second drum load sensor and the oil sand feedrate sensor.

FIELD OF INVENTION

The present invention relates to an apparatus for processing oil sand toproduce a liquid stream comprising water and bitumen and a solid streamcomprising solid particles. The present invention further relates to acontrol system for the apparatus and a method for controlling theapparatus.

BACKGROUND OF INVENTION

Oil sand is essentially a matrix of bitumen, mineral matter and water.The bitumen component of oil sand consists of viscous hydrocarbons whichbehave much like a solid at normal in situ temperatures and which act asa binder for the other components of the oil sand matrix. The mineralmatter component of oil sand typically consists largely of sand, but mayalso include rock, silt and clay. Sand and rock are considered to becoarse mineral matter, while clay and silt are considered to be finemineral matter, where fines are defined as mineral matter having aparticle size of less than 44 microns. The water component of oil sandconsists essentially of a film of connate water surrounding the sand inthe oil sand matrix, and may also contain particles of fine mineralmatter within it.

A typical deposit of oil sand will contain about 10% to 12% bitumen andabout 3% to 6% water, with the remainder of the oil sand being made upof solid mineral matter particles. Typically the mineral mattercomponent in oil sand will contain about 14% to 20% fines, measured byweight of total mineral matter contained in the deposit, but the amountof fines may increase to about 30% or more for poorer quality deposits.Oil sand extracted from the Athabasca area near Fort McMurray, Alberta,Canada, averages about 11% bitumen, 5% water and 84% mineral matter,with about 15% to 20% of the mineral matter being made up of fines.

Oil sand deposits are mined for the purpose of extracting bitumen fromthe oil sand, which bitumen is then upgraded to synthetic crude oil.Accordingly, various processes have been developed for extracting thebitumen from the oil sand.

For instance, conventionally, a “hot water process” is used forextracting bitumen from oil sand in which both aggressive thermal actionand aggressive mechanical action are used to liberate and separatebitumen from the oil sand. The hot water process is a three stepprocess. First, the oil sand is conditioned by mixing it with hot waterat about 95° Celsius and steam in a conditioning vessel which vigorouslyagitates the resulting slurry in order to completely disintegrate theoil sand. Second, once the disintegration is complete, the slurry isseparated by allowing the sand and rock to settle out, and the bitumen,having air entrained within it, floats to the top of the slurry and iswithdrawn as a bitumen froth. Third, the remainder of the slurry, whichis referred to as the middlings, is then treated further or scavenged byfroth flotation techniques to recover bitumen that did not float to thetop of the slurry during the separation step.

To assist in the recovery of bitumen during the separation step, sodiumhydroxide (caustic) is typically added to the slurry during theconditioning step in order to maintain the pH of the slurry slightlybasic, in the range of 8.0 to 8.5. This has the effect of chemicallydispersing the clay that becomes dispersed in the slurry during theconditioning step, which in turn reduces the viscosity of the slurry byreducing the particle size of the clay minerals present in the slurry.With the clay present in the slurry chemically dispersed and theviscosity of the slurry lowered, the bitumen more readily floats to thesurface of the slurry and can therefore be more readily recovered duringthe separation step.

There are several disadvantages to the hot water process. The use of hotwater and steam in the process, as well as the vigorous agitation towhich the oil sand is subjected during the conditioning step, mean thatthe energy requirements of the process are very high. In addition, sincethe main goal of the hot water process is to liberate and separatebitumen from the oil sand by completely destroying the oil sand matrix,most of the fine mineral matter contained in the oil sand becomesmechanically dispersed throughout the slurry during the conditioningstep.

The addition of caustic to the slurry to reduce the viscosity of theslurry results in further chemical dispersal of the clay in the finemineral matter, whereby the size of the individual clay particles may bereduced to as small as 0.2 microns. The combination of the vigorous andcomplete physical dispersal of the fines contained in the oil sand andthe chemical dispersal of the clay in the resulting slurry create amiddlings stream that may contain a large amount of very well dispersedfines held in suspension, particularly where the oil sand deposit is oflower quality and therefore has a relatively high fines content. As thefines content of the oil sand feedstock increases, the concentration offines in the slurry increases, and recovery of bitumen from the slurrybecomes more difficult, since the suspended fine particles tend to“trap” bitumen within the slurry.

In addition to the problems regarding the recovery of bitumen fromslurries containing a large amount of dispersed fines, the middlingsstream that remains following the scavenging step poses a huge disposalproblem, since it constitutes a sludge that tends to settle andconsolidate very slowly. Typically, the practice for the disposal of thesludge remaining after the scavenging step involves pumping it into hugetailing ponds, where the fines slowly settle and stratify. After severalweeks, some of the water forming the sludge will be present at the topof the tailing pond containing only a small amount of suspended fines.This water may be recycled for use in the hot water process, after beingreheated to the process temperature.

In any event, because of the characteristics of the middlings sludge,the tailing ponds cannot be completely rehabilitated for many, manyyears, and only a portion of the water that enters the tailing ponds canbe recovered and reused in the hot water process, thus creating arequirement that a large amount of makeup water be available for the hotwater process to make up for the water that is lost to the tailingponds.

Some attempts have been made to improve upon the hot water process, suchas: Canadian Patent No. 1,085,761 issued on Sep. 16, 1980 to Rendall;U.S. Pat. No. 4,512,956 issued on Apr. 23, 1985 to Robinson et al; U.S.Pat. No. 4,533,459 issued on Aug. 6, 1985 to Dente et al; U.S. Pat. No.4,414,117 issued on Nov. 8, 1983 to Yong et al; and U.S. Pat. No.4,225,433 issued Sep. 30, 1980 to Liu et al. However, none of theseattempts have been found to be fully satisfactory.

The challenge remains to extract bitumen from oil sand in a mannermaximizing the recovery of bitumen while minimizing the amount of sludgethat is generated, and while controlling the physical characteristics ofthe sludge so that it may be more easily disposed of. It is alsodesirable to minimize the energy requirements of the process as much aspossible so that the process can be carried out in an economical andenvironmentally acceptable manner.

In this regard, Canadian Patent Application No. 2,030,934 published onMay 28, 1992 by Strand and Canadian Patent Application No. 2,124,199published on Jun. 11, 1992 by Strand, both describe an extractionapparatus and process employing a countercurrent separator vessel inwhich oil sand is gently rolled from one end to the other by a spiralribbon and mixer elements while hot water, defined as having atemperature of 50° Celsius, circulates in the opposite direction. Twostreams are then removed from opposite ends of the separator vessel. Onestream contains coarse material and some water, while the other streamcontains bitumen and dispersed fines in a slurry. Mechanical action isminimized and liberation and separation of bitumen is accomplishedalmost entirely by thermal action.

It is stated in these applications that an important objective of theinvention is to leave most of the clay in the oil sand in its originalstate so that it may be returned along with separated coarse material,to the site from which the oil sand was mined. It is also stated thatdue to limited dispersal of clay in the process water, it should notnormally be necessary to add caustic to aid in the recovery of bitumen,and a substantial portion of the process water will be available forrecycling. As for the amount of process water required, it is statedthat the water to oil sand ratio is a function of the heat transferrequirements of the system, and not the requirement to provide adequatedilution of the slurry to facilitate bitumen recovery.

Further, Canadian Patent No. 2,123,076 issued Nov. 17, 1998 to Strandet. al. utilizes the countercurrent separator vessel of the previouslynoted Canadian Patent Applications in the performance of an improved oilsand extraction process. Specifically, Strand et. al. describes anoverall method for processing lumps of oil sand containing bitumen toproduce a bitumen froth and non segregating tailings of a solid materialand a sludge.

The method includes depositing the lumps of oil sand into a bath of warmwater. The lumps are then conditioned by gently contacting them with thewarm water to liberate and separate bitumen from the oil sand whileminimizing the dispersal into the bath of fine material contained in theoil sand. The conditioning step is preferably performed utilizing thepreviously described countercurrent separator vessel, as shown in FIGS.2 and 3 of Canadian Patent No. 2,123,076.

Following conditioning, the solid material remaining after theliberation and separation of the bitumen from the oil sand is removedfrom the bath and collected for further processing. The warm watercontaining bitumen and dispersed fine material is also removed from thebath and collected for further processing.

Following removal from the bath, the warm water containing bitumen anddispersed fine material is separated into the bitumen froth and asuspension of dispersed fine material. The suspension of dispersed finematerial is dewatered to produce the sludge, which is combined with thesolid material to produce the tailings. Preferably, the sludge iscombined with the solid material in a mixing drum as shown in FIG. 4 ofCanadian Patent No. 2,123,076.

The stated goal of Canadian Patent No. 2,123,076 is to eliminate orreduce the need for sludge tailing ponds which typically occupy manysquare kilometers, and replace the sludge currently disposed of in thesetailing ponds with nonsegregating tailings produced from both the solidmaterial generated by the extraction process and the sludge generated bythe extraction process. In order to minimize the energy requirements ofthe described process, the thermal and mechanical energy input into theprocess are limited, while also limiting the amount of thermal energythat is lost during the process to the various product and wastestreams.

However, there continues to be a need for improvements to be made to theoil sand processing methods and apparatuses in order to increase theefficiencies and to enhance or improve upon the characteristics orqualities of the resulting products of such methods and apparatuses.

Accordingly, there is a need in the industry for an improved apparatusfor processing oil sand to produce a liquid stream and a solids streamhaving desirable characteristics or qualities. Further, to enhance orfacilitate the efficient operation of the improved apparatus, there is aneed for an improved control system and method for controlling theapparatus.

SUMMARY OF INVENTION

The present invention relates to an apparatus for processing oil sand toproduce a liquid stream comprising water and bitumen and a solid streamcomprising solid particles. Further, the present invention relates to acontrol system for an apparatus for processing oil sand to produce aliquid stream comprising water and bitumen and a solid stream comprisingsolid particles. Finally, the present invention relates to a method forcontrolling an apparatus for processing oil sand to produce a liquidstream comprising water and bitumen and a solid stream comprising solidparticles.

Although the control system may be used with any compatible oil sandprocessing apparatus, in the preferred embodiment the control system isfor use with the apparatus of the present invention. Similarly, althoughthe method may be used for controlling any compatible oil sandprocessing apparatus, in the preferred embodiment the method is forcontrolling the apparatus of the present invention.

As discussed above, oil sand is comprised of a matrix of bitumen, solidparticles and water. The bitumen is comprised of heavy oil or viscoushydrocarbons which typically behave much like a solid at normal in situtemperatures and which act as a binder for the other components of theoil sand matrix. The solid particles are comprised of mineral matterincluding sand, rock, silt and clay. Sand and rock are considered to becoarse mineral matter, while clay and silt are considered to be finemineral matter, where fines are defined as mineral matter having aparticular size of less than 44 microns. The water is typicallycomprised of a film of connate water surrounding the sand in the oilsand matrix, and may also include particles of fine mineral matter.

The apparatus is provided for processing the oil sand to produce aliquid stream comprising water and bitumen and a solid stream comprisingsolid particles. The liquid stream is comprised of water and bitumen andis typically produced as a “bitumen froth.” The bitumen froth will becomprised largely of bitumen, but will also include an amount of waterand an amount of fine mineral matter which is not able to be separatedfrom the bitumen during the processing of the oil sand. The solid streamis comprised of solid particles including both fine and course mineralmatter.

In a first aspect of the invention in its apparatus form, the inventionis comprised of an apparatus for processing oil sand to produce a liquidstream comprising water and bitumen and a solid stream comprising solidparticles, the apparatus comprising:

-   -   (a) a generally cylindrical drum having a first end, a second        end and an interior surface, the drum comprising a conditioning        zone adjacent to the first end, a compressing zone adjacent to        the second end, and a processing zone between the conditioning        zone and the compressing zone;    -   (b) a rotatable spiral trough extending along the interior        surface of the drum through the conditioning zone, the        processing zone and the compressing zone, for imparting a spiral        rolling motion to the oil sand, the spiral trough having a        width, wherein the width of the spiral trough through the        compressing zone is less than the width of the spiral trough        through the processing zone;    -   (c) a plurality of lifting members oriented generally        transversely within and spaced along the spiral trough, for        lifting the oil sand as the spiral trough rotates;    -   (d) an oil sand inlet, wherein the oil sand inlet communicates        with the conditioning zone of the drum;    -   (e) a liquid stream outlet for the drum located at the first end        of the drum;    -   (f) a water inlet, wherein the water inlet communicates with the        processing zone of the drum;    -   (g) a solid stream outlet for the drum located adjacent to the        second end of the drum such that the compressing zone is located        between the processing zone and the solid stream outlet; and    -   (h) a drive mechanism for rotating the spiral trough.

In a second aspect of the invention in its apparatus form, the inventionis comprised of an apparatus for processing oil sand to produce a liquidstream comprising water and bitumen and a solid stream comprising solidparticles, the apparatus comprising:

-   -   (a) a generally cylindrical drum having a first end, a second        end and an interior surface, the drum comprising a conditioning        zone adjacent to the first end, a compressing zone adjacent to        the second end, and a processing zone between the conditioning        zone and the compressing zone;    -   (b) a rotatable spiral trough extending along the interior        surface of the drum through the conditioning zone, the        processing zone and the compressing zone, for imparting a spiral        rolling motion to the oil sand, the spiral trough having a        height, wherein the height of the spiral trough through at least        a portion of the compressing zone is greater than the height of        the spiral trough through both the processing zone and the        conditioning zone;    -   (c) a plurality of lifting members oriented generally        transversely within and spaced along the spiral trough, for        lifting the oil sand as the spiral trough rotates;    -   (d) an oil sand inlet, wherein the oil sand inlet communicates        with the conditioning zone of the drum;    -   (e) a liquid stream outlet for the drum located at the first end        of the drum;    -   (f) a water inlet, wherein the water inlet communicates with the        processing zone of the drum;    -   (g) a solid stream outlet for the drum located adjacent to the        second end of the drum such that the compressing zone is located        between the processing zone and the solid stream outlet; and    -   (h) a drive mechanism for rotating the spiral trough.

In a third aspect of the invention in its apparatus form, the inventionis comprised of an apparatus for processing oil sand to produce a liquidstream comprising water and bitumen and a solid stream comprising solidparticles, the apparatus comprising:

-   -   (a) a generally cylindrical drum having a first end, a second        end and an interior surface, the drum comprising a conditioning        zone adjacent to the first end, a compressing zone adjacent to        the second end, and a processing zone between the conditioning        zone and the compressing zone;    -   (b) a rotatable spiral trough extending along the interior        surface of the drum through the conditioning zone, the        processing zone and the compressing zone, for imparting a spiral        rolling motion to the oil sand;    -   (c) a plurality of lifting members oriented generally        transversely within and spaced along the spiral trough, for        lifting the oil sand as the spiral trough rotates;    -   (d) an oil sand inlet, wherein the oil sand inlet communicates        with the conditioning zone of the drum;    -   (e) a liquid stream outlet for the drum located at the first end        of the drum;    -   (f) a water inlet, wherein the water inlet communicates with the        processing zone of the drum;    -   (g) a solid stream outlet for the drum located adjacent to the        second end of the drum such that the compressing zone is located        between the processing zone and the solid stream outlet, wherein        the solid stream outlet is comprised of the drum defining a        plurality of perforations in the drum which provide a screen        section of the drum, and wherein the perforations are sized so        that the solid particles having a size less than or equal to a        desired maximum size may exit the drum through the perforations;        and    -   (h) a drive mechanism for rotating the spiral trough.

Thus, in all aspects of the present invention in its apparatus formincluding those specific preferred aspects as noted above, the apparatusis comprised of:

-   -   (a) a generally cylindrical drum having a first end, a second        end and an interior surface, the drum comprising a conditioning        zone adjacent to the first end, a compressing zone adjacent to        the second end, and a processing zone between the conditioning        zone and the compressing zone;    -   (b) a rotatable spiral trough extending along the interior        surface of the drum through the conditioning zone, the        processing zone and the compressing zone, for imparting a spiral        rolling motion to the oil sand;    -   (c) a plurality of lifting members oriented generally        transversely within and spaced along the spiral trough, for        lifting the oil sand as the spiral trough rotates;    -   (d) an oil sand inlet, wherein the oil sand inlet communicates        with the conditioning zone of the drum;    -   (e) a liquid stream outlet for the drum located at the first end        of the drum;    -   (f) a water inlet, wherein the water inlet communicates with the        processing zone of the drum;    -   (g) a solid stream outlet for the drum located adjacent to the        second end of the drum such that the compressing zone is located        between the processing zone and the solid stream outlet; and    -   (h) a drive mechanism for rotating the spiral trough.

Thus, the apparatus provides for countercurrent separation of the oilsand. Specifically, the oil sand is introduced to the conditioning zoneadjacent the first end of the drum. The solid particles are transportedthrough the drum by the action of the spiral trough for expulsionthrough the solid stream outlet adjacent the second end of the drum.Water is introduced through the water inlet to the processing zonebetween the conditioning zone and the compressing zone adjacent to thesecond end of the drum. The bitumen is transported through the drum bythe movement of the water towards the first end of the drum forexpulsion through the liquid stream outlet.

The drum is generally cylindrical to facilitate transport of the solidparticles through the drum. The generally cylindrical drum may beconstructed of material which is rolled or otherwise formed into agenerally cylindrical shape. Alternatively, the generally cylindricaldrum may be constructed of flat panels or sheets of a material which areconnected together by welding or by some other means to provide agenerally cylindrical shape, in which case the number of flat panels orsheets is preferably maximized in order to provide a closerapproximation to a cylindrical shape. For example, it is contemplatedthat about sixteen flat panels or sheets welded together would provide asuitable generally cylindrical shape while reducing the fabricationcosts associated with rolling or forming the material into a generallycylindrical shape. More than sixteen or fewer than sixteen flat panelsor sheets may, however, be used in similar manner to provide thegenerally cylindrical shape.

As indicated, the drum includes a conditioning zone, a processing zoneand a compressing zone. The oil sand inlet communicates with theconditioning zone which is located at or adjacent to the first end ofthe drum. The conditioning zone is provided primarily to permit the oilsand to first contact, or be introduced to, the water in order tocommence the liberation and separation of the bitumen from the oil sandwithin the spiral trough.

The water inlet communicates with the processing zone which is locatedbetween the conditioning zone and the compressing zone. The processingzone is provided to agitate the oil sand within the spiral trough andfurther contact the oil sand with the water in order to enhance theextraction or liberation of the bitumen to provide the separated solidsparticles comprising the solid stream, while also expelling some of thewater from the solid stream moving towards the second end of the drum.

The water inlet may communicate with the processing zone at any positionor location therein permitting the processing zone to perform itsintended function as described herein. However, preferably, the spiraltrough through the processing zone defines a processing zone inlet and aprocessing zone outlet and wherein the water inlet communicates with theprocessing zone at a location adjacent to the processing zone outlet.This preferred location of the water inlet is intended to maximize theexposure of the oil sand to the water within the drum by increasing thelength or portion of the processing zone which is exposed to the wateras the water flows from the water inlet towards the first end of thedrum.

The compressing zone is located at or adjacent to the second end of thedrum between the processing zone and the solid stream outlet. Thecompressing zone is provided to compress the oil sand within the spiraltrough moving towards the second end to expel any excess or residualwater within the solid stream prior to exiting from the drum through thesolid stream outlet.

The spiral trough extends through each of the conditioning, processingand compressing zones in order to impart a spiral rolling motion to theoil sand through the drum from the first end towards the second end. Thespiral trough may extend along the interior surface of the drum for anydesired number of revolutions capable of performing the intendedfunctions of each of the conditioning, processing and compressing zones.Preferably, the spiral trough extends along the interior surface of thedrum for between about five and about twenty revolutions of the drum. Inthe preferred embodiment, the spiral trough extends along the interiorsurface of the drum for about fourteen revolutions of the drum.

The spiral trough may be rotated in any manner to impart the desiredspiral rolling motion to the oil sand and may be rotated by anycompatible drive mechanism capable of rotating the spiral trough. Forinstance, the spiral trough may be adapted to be supported within thedrum such that the spiral trough is rotated within, and relative to, theinterior surface of the drum. In other words, the drum may remainstationary while the spiral trough is rotated therein. In this instance,the drive mechanism would be operatively connected with the spiraltrough.

However, preferably, the spiral trough is fixed to the drum so thatrotation of the drum rotates the spiral trough and wherein the drivemechanism rotates the drum. In other words, the drive mechanism isoperatively connected with the drum and the drum and the spiral troughare rotated together to impart the spiral rolling motion to the oilsand.

The spiral trough has a width and the width of the spiral trough in eachof the conditioning, processing and compressing zones is preferablyselected to facilitate or enhance the intended function of thatrespective zone. In the preferred embodiment, the width of the spiraltrough through the compressing zone is less than the width of the spiraltrough through the processing zone.

Within the processing zone, the width of the spiral trough is selected,at least in part, to accommodate the amount of water entering theprocessing zone through the water inlet and such that the solidparticles are substantially retained within the spiral trough tominimize the flow of any solid particles within the water towards thefirst end of the drum.

Within the compressing zone, the width of the spiral trough is selected,at least in part, to compress the oil sand or solid stream within thespiral trough in order to expel any excess or residual water from thesolid particles. However, the width is also selected with regard to theanticipated amount of solid particles to be contained or moved withinthe spiral trough through the compressing zone and the anticipated sizeof the solid particles within the compressing zone such that the spiraltrough is able to accommodate the solid particles therein.

Thus, as a result of the different functions of the processing andcompressing zones, the width of the spiral trough through thecompressing zone is less than the width of the spiral trough through theprocessing zone. Additionally, the spiral trough through the compressingzone preferably defines a compressing zone inlet and a compressing zoneoutlet and wherein the width of the spiral trough at the compressingzone outlet is less than the width of the spiral trough at thecompressing zone inlet. As a result, in the direction from thecompressing zone inlet towards the compressing zone outlet, the oil sandor solid stream within the spiral trough is increasingly compressed orgradually further compressed in order to facilitate the expulsion of anyexcess or residual water from the solid particles.

Further, in the preferred embodiment, the width of the spiral troughthrough the processing zone is less than the width of the spiral troughthrough the conditioning zone. Within the conditioning zone, the widthof the spiral trough is selected to accommodate the amount of oil sandentering the conditioning zone such that the spiral trough is able tosubstantially accommodate the oil sand therein, while enhancing thecontact between the water and the oil sand. Thus, as a result of thedifferent functions of the processing and conditioning zones, the widthof the spiral trough through the processing zone is less than the widthof the spiral trough through the conditioning zone.

In addition, the spiral trough has a height and the height of the spiraltrough in each of the conditioning, processing and compressing zones isalso preferably selected to facilitate or enhance the intended functionof that respective zone.

In the preferred embodiment, the height of the spiral trough through atleast a portion of the compressing zone is greater than the height ofthe spiral trough through both the conditioning zone and the processingzone. Within the compressing zone, the height of the spiral trough isselected, at least in part, to inhibit or prevent the flow of the liquidstream and any water from the processing zone towards the compressingzone. Specifically, as described, the water enters the processing zonethrough the water inlet and the resulting liquid stream preferably flowsin the direction of the first end of the drum and the liquid streamoutlet. Thus, the relative heights of the spiral trough through each ofthe zones is selected to facilitate the flow of the liquid streamtowards the liquid stream outlet. The greater height of the spiraltrough in the compressing zone, as compared with both the conditioningzone and the processing zone, prevents or inhibits the undesirablebackflow of the liquid stream or flow of the liquid stream towards thesolid stream outlet at the second end of the drum.

As well, the liquid stream outlet has a height and wherein the height ofthe spiral trough through at least a portion of the compressing zone isgreater than the height of the liquid stream outlet. The height of theliquid stream outlet is selected, at least in part, for similar reasonsas the selection of the relative heights of the spiral trough throughthe zones. Specifically, the height of the liquid stream outlet isselected to facilitate the flow of the liquid stream away from thecompressing zone and towards the liquid stream outlet and to reduce orminimize any undesirable backflow of the liquid stream to thecompressing zone.

Additionally, the height of the spiral trough in the compressing zone isselected, in combination with the width, having regard to theanticipated amount of solid particles to be contained or moved withinthe spiral trough through the compressing zone such that the spiraltrough is able to accommodate the solid particles therein for movementin the direction of the sold stream outlet.

As indicated above, the spiral trough through the compressing zonepreferably defines a compressing zone inlet and a compressing zoneoutlet. Preferably, the height of the spiral trough at the compressingzone outlet is greater than the height of the spiral trough at thecompressing zone inlet. The increased height of the spiral trough fromthe compressing zone inlet to the compressing zone outlet furtherinhibits any undesirable backflow of the liquid stream towards thesecond end of the drum. As well, given that the width of the spiraltrough at the compressing zone outlet is less than the width at thecompressing zone inlet, the height of the spiral trough at thecompressing zone outlet is preferably greater than the height at thecompressing zone inlet in order to permit the spiral trough toaccommodate the anticipated amount or quantity of the solid particles orsolid stream to be contained therein.

Thus, in the preferred embodiment, the spiral trough in each of theconditioning, processing and compressing zones has a width and a heightwhich are selected together, or having regard to each other, such thatthe zone is capable of performing its respective intended functions. Inother words, the spiral trough has a transverse cross-sectional area.Thus, the cross-sectional area of the spiral trough in each zone ispreferably selected such that the zone is capable of performing itsintended functions. For instance, in the preferred embodiment, thetransverse cross-sectional area of the spiral trough through thecompressing zone is preferably less than the transverse cross-sectionalarea of the spiral trough through the processing zone.

In addition, the drum is preferably further comprised of a froth poolingsection located between the first end of the drum and the conditioningzone of the drum. The froth pooling section is preferably configured topermit the liquid stream to further separate prior to exiting the drumthrough the liquid stream outlet. In other words, any solid particlesthat may be contained within, or that have been carried along by, theliquid stream are permitted to settle within the froth pooling sectionand to separate from the water and bitumen, also known as the bitumenfroth. As a result, the amount of solid particles carried out throughthe liquid stream outlet with the bitumen froth may be reduced orminimized. Given the desire to permit the solid particles to separateand settle within the froth pooling section, preferably, the spiraltrough does not extend through the froth pooling section.

As indicated, the apparatus includes a plurality of lifting membersoriented generally transversely within and spaced along the spiraltrough. The lifting members are configured, sized and spaced in each ofthe zones of the drum to lift the oil sand as the spiral trough rotates.The configuration, sizing and spacing of the lifting members may varybetween each of the conditioning, processing and compressing zones, ormay be the same through two or more zones, as necessary or desired topermit each zone to perform its respective intended functions.

However, preferably, the lifting members are spaced along the spiraltrough so that the lifting members are distributed around thecircumference of the interior surface of the drum. Further, the liftingmembers are preferably distributed at least about every 90 degrees aboutthe circumference. In the preferred embodiment, the lifting members aredistributed about every 55 degrees about the circumference through eachof the conditioning, processing and compressing zones.

Further, the lifting members have a height and the height of the liftingmembers in each of the conditioning, processing and compressing zones ispreferably selected to facilitate or enhance the intended function ofthe respective zone. For instance, preferably, the height of the liftingmembers through the compressing zone is less than the height of thelifting members through the processing zone. The height of the liftingmembers in the processing zone is selected, at least in part, tocontribute to the desired agitation of the oil sand within the spiraltrough and contact between the oil sand and the water in order toenhance the extraction or liberation of the bitumen. The height of thelifting members in the compressing zone is selected, at least in part,to move or transport the solid stream towards the solid stream outlet.Less agitation of the oil sand is desirable within the compressing zone.

The apparatus may be further comprised of a drum flocculant inletcommunicating with the drum. The drum flocculant inlet is provided forintroducing a flocculant to the oil sand as the oil sand is contactedwith the water introduced through the water inlet. The flocculant aidsor facilitates the agglomeration or precipitation of the fine mineralmatter comprising the solid particles. The use of the flocculant mayalso increase the amount of bitumen which is recovered from the oilsand. Although the drum flocculant outlet may communicate with any zoneof the drum, preferably, the drum flocculant inlet communicates with theprocessing zone of the drum. The drum flocculant inlet may also becombined with the water inlet so that the drum flocculant inlet iscomprised of the water inlet. Thus, the oil sand from the oil sand inletmay be contacted and mixed with both the water and the flocculant withinthe conditioning zone prior to being subjected to further processing.

As well, the drum may be further comprised of a solid particle mixingsection for mixing the solid particles contained within the drum with atleast one additive, wherein the solid particle mixing section is locatedbetween the compressing zone and the second end of the drum. The solidparticle mixing section is preferably downstream of the compressingzone, or nearer the second end of the drum than the compressing zone, sothat a significant or substantial amount of the water has been expelledfrom the solid particles by the compressing zone prior to further mixingof the solid particles with the desired additive or additives.

Any additive desired to be mixed with the solid particles to facilitatethe further processing of the solid stream or to enhance the desiredproperties or characteristics of the solid stream may be utilized.Preferably, the additive is comprised of at least one of a flocculantand a sludge. In the preferred embodiment, both a flocculant and asludge are mixed with the solid particles by the solid particle mixingsection.

Thus, in the preferred embodiment, the solid particle mixing section iscomprised of a sludge inlet zone and a flocculant inlet zone and theapparatus is further comprised of a mixing section sludge inletcommunicating with the sludge inlet zone and a mixing section flocculantinlet communicating with the flocculant inlet zone. Accordingly, thesludge is introduced to the sludge inlet zone via the mixing sectionsludge inlet, while the flocculant is introduced to the flocculant inletzone via the mixing section flocculant inlet.

The flocculant inlet zone and the sludge inlet zone may be concurrent inthat both the flocculant and the sludge may be introduced to the solidparticles at approximately the same time. Alternatively, the flocculantinlet zone and the sludge inlet zone may be disposed or arranged withinthe solid particle mixing section in any order. However, preferably, thesludge inlet zone is located between the flocculant inlet zone and thesecond end of the drum. Thus, the flocculant is introduced to, and mixedwith, the solid particles prior to introducing and mixing the sludgewith the solid particles.

Preferably, the spiral trough extends through the solid particle mixingsection. Thus, the spiral trough imparts a spiral rolling motion to thesolid particles within the solid particle mixing section in order tofacilitate or enhance the mixing of the additives, and particularly theflocculant and the sludge, with the solid particles.

The width of the spiral trough through the solid particle mixing sectionis selected to facilitate or enhance its intended function. Preferably,the width of the spiral trough through the solid particle mixing sectionis greater than the width of the spiral trough through the compressingzone of the drum.

Within the solid particle mixing section, the width of the spiral troughis selected, at least in part, to accommodate the solid particlesentering the solid particle mixing section from the compressing zone, aswell as the amounts of flocculant and sludge entering the solid particlemixing section through the mixing section flocculant inlet and themixing section sludge inlet. Further, the selected width preferablypermits the solid particles to be retained in the spiral trough duringthe mixing thereof with the flocculant and sludge so that the solidparticles are substantially conveyed towards the second end of the drum.

In addition, the height of the spiral trough through the solid particlemixing section is also selected to facilitate or enhance its intendedfunction. Preferably, the height of the spiral trough through the solidparticle mixing section is substantially similar to the height of thespiral trough through the compressing zone of the drum.

Within the solid particle mixing section, the height of the spiraltrough is selected, at least in part, to further inhibit or prevent theflow of the liquid stream and any water from the processing zone towardsthe solid particle mixing section. Additionally, the height of thespiral trough in the solid particle mixing section is selected, incombination with the width, having regard to the anticipated amount ofsolid particles, flocculant and sludge to be conveyed through and mixedwithin the spiral trough. In other words, the cross-sectional area ofthe spiral trough in the solid particle mixing section is selected suchthat the solid particle mixing section is capable of performing itsintended function as described herein.

Finally, the lifting members are preferably continued along the spiraltrough through the solid particle mixing section. The plurality oflifting members are oriented generally transversely within and spacedalong the spiral trough through the solid particle mixing section. Thelifting members are configured, sized and spaced in the solid particlemixing section to lift the solid particles as the spiral trough rotatesand to facilitate or enhance the intended function of the solid particlemixing section.

The configuration, sizing and spacing of the lifting members in thesolid particle mixing sectional may be similar to, or vary from, that ofthe lifting members in any or all of the conditioning, processing andcompressing zones of the drum. Preferably, the configuration, sizing andspacing of the lifting members in the solid particle mixing section aresubstantially similar to the configuration, sizing and spacing of thelifting members in the compressing zone.

Thus, in the preferred embodiment, the lifting members are distributedabout every 55 degrees about the circumference of the interior surfaceof the drum through the solid particle mixing section. Further, theheight of the lifting members through the solid particle mixing sectionis substantially similar to the height of the lifting members throughthe compressing zone.

The solid stream outlet may be comprised of any structure or mechanismsuitable for expelling or discharging the solid stream from the drum.For instance, the solid stream outlet may be defined by or comprised ofany portion or component of the drum. As well, the solid stream outletmay be comprised of a single outlet or discharge mechanism such that allof the solid particles are discharged concurrently. Alternately, thesolid stream outlet may be comprised of a plurality of outlets ordischarge mechanisms such that the solid particles are sorted orseparated in some manner prior to being discharged. In the preferredembodiment, the solid particles are sorted or separated according toparticle size prior to being discharged or expelled through the solidstream outlet.

In particular, the solid stream outlet is preferably comprised of thedrum defining a plurality of perforations in the drum which provide ascreen section of the drum, and wherein the perforations are sized sothat the solid particles having a size less than or equal to a desiredmaximum size may exit the drum through the perforations. In addition,the solid stream outlet is further comprised of an oversized particleoutlet located at the second end of the drum whereby the solid particleshaving a size greater than the desired maximum size may exit the drumthrough the oversized particle outlet. Oversized particles from theoversized particle outlet may be directed to the same location as othersolid particles from the solid stream outlet, or may be directed to adifferent location.

Preferably, the spiral trough extends through the screen section of thedrum. The spiral trough imparts a spiral rolling motion to the solidparticles within the screen section in order to facilitate and enhancethe sorting and exiting through the perforations of the solid particleshaving a size less than or equal to the desired maximum size. Further,the action of the spiral trough also facilitates the exiting of thesolid particles having a size greater than the desired maximum sizethrough the oversized particle outlet.

The width and the height, and thus the cross-sectional area, of thespiral trough through the screen section are selected to facilitate orenhance its intended function. Thus, within the screen section, thewidth and the height of the spiral trough are selected, at least inpart, to be capable of conveying the solid particles therethrough, whilepermitting the different sized particles to exit from either theperforations of the screen section or the oversized particle outlet atthe second end of the drum.

Preferably, the width of the spiral trough through the screen section isabout the same as or less than the width of the spiral trough throughthe immediately preceding zone or section of the drum. For instance, ifa solid particle mixing section is present, the width of the spiraltrough through the screen section is preferably less than the width ofthe spiral trough through the solid particle mixing section. If a solidparticle mixing section is not present, the width of the spiral troughthrough the screen section is about the same as the width of the spiraltrough through at lest a portion of the compressing zone.

The height of the spiral trough through the screen section is preferablyless than the height of the spiral trough through the immediatelypreceding zone or section of the drum, being either the compressing zoneof the drum or the solid particle mixing section. The decreased heightof the spiral trough tends to facilitate the movement of the solidparticles through the screen section.

Further, in order to facilitate the sorting of the particles sizes andexiting through either the screen section or the oversized particleoutlet, preferably, the lifting members are not provided in the screensection of the drum. Lifting of the solid particles would tend tointerfere with or impede the intended function of the solid streamoutlet, and particularly the screen section.

As indicated, the drum may or may not be comprised of the solid particlemixing section. Where the drum does not include a solid particle mixingsection, the screen section is located adjacent the compressing zone ofthe drum. Where the drum is further comprised of a solid particle mixingsection for mixing the solid particles contained within the drum with atleast one additive, the solid particle mixing section is located betweenthe compressing zone and the screen section of the drum. In this case,the sludge inlet zone is located between the flocculant inlet zone andthe screen section of the drum.

As indicated previously, in a further aspect of the invention, theinvention relates to a control system for an apparatus for processingoil sand to produce a liquid stream comprising water and bitumen and asolid stream comprising solid particles. Preferably, the control systemis for the apparatus of the invention as described herein, andpreferably is provided for the preferred embodiment of the apparatus.

Further, in a final aspect of the invention, the invention relates to amethod for controlling an apparatus for processing oil sand to produce aliquid stream comprising water and bitumen and a solid stream comprisingsolid particles. As with the control system, the controlling method ispreferably provided for controlling the apparatus of the invention asdescribed herein, and more preferably is provided for controlling thepreferred embodiment of the apparatus.

More particularly, in the aspect of the invention related to the controlsystem, the invention is comprised of a control system for an apparatusfor processing oil sand to produce a liquid stream comprising water andbitumen and a solid stream comprising solid particles, wherein theapparatus is comprised of a generally cylindrical rotatable drum, aspiral trough extending along an interior surface of the drum, an oilsand feed mechanism, a drive mechanism for rotating the drum, a firstdrum support for supporting the drum, and a second drum support forsupporting the drum, wherein the drum is comprised of a first end, asecond end, an oil sand inlet located adjacent to the first end, and asolid stream outlet located adjacent to the second end, wherein thefirst drum support is located between the first end of the drum and amidpoint of the drum, and wherein the second drum support is locatedbetween the second end of the drum and the midpoint of the drum, thecontrol system comprising:

-   -   (a) a first drum load sensor associated with the first drum        support, for sensing a first drum load exerted on the first drum        support;    -   (b) a second drum load sensor associated with the second drum        support, for sensing a second drum load exerted on the second        drum support;    -   (c) an oil sand feedrate sensor associated with the oil sand        feed mechanism, for sensing a feedrate of the oil sand feed        mechanism;    -   (d) a controller operatively connected with the first drum load        sensor, the second drum load sensor, the oil sand feedrate        sensor, the drive mechanism and the oil sand feed mechanism, for        controlling a rotation speed of the drum and a feedrate of the        oil sand feed mechanism in response to input data from the first        drum load sensor, the second drum load sensor and the oil sand        feedrate sensor.

Further, in the aspect of the invention related to the controllingmethod, the invention is comprised of a method for controlling anapparatus for processing oil sand to produce a liquid stream comprisingwater and bitumen and a solid stream comprising solid particles, whereinthe apparatus is comprised of a generally cylindrical rotatable drum, aspiral trough extending along an interior surface of the drum, an oilsand feed mechanism, a drive mechanism for rotating the drum, a firstdrum support for supporting the drum, and a second drum support forsupporting the drum, wherein the drum is comprised of a first end, asecond end, an oil sand inlet located adjacent to the first end, and asolid stream outlet located adjacent to the second end, wherein thefirst drum support is located between the first end of the drum and amidpoint of the drum, and wherein the second drum support is locatedbetween the second end of the drum and the midpoint of the drum, themethod comprising:

-   -   (a) sensing a first drum load exerted on the first drum support;    -   (b) sensing a second drum load exerted on the second drum        support;    -   (c) sensing a feedrate of the oil sand feed mechanism; and    -   (d) controlling a rotation speed of the drum and a feedrate of        the oil sand feed mechanism in response to input data from the        first drum load sensing step, the second drum load sensing step        and the feedrate sensing step.

As indicated, the apparatus includes an oil sand feed mechanism and adrive mechanism for rotating the drum. The oil sand feed mechanism maybe comprised of any mechanism or device capable of feeding or deliveringthe oil sand to the drum at a desired feedrate. The drive mechanism maybe comprised of any mechanism or device capable of rotating the drum ata desired rotation speed.

Further, the apparatus includes a first drum support for supporting thedrum and a second drum support for supporting the drum. Moreparticularly, a first drum load is exerted on the first drum support,while a second drum load is exerted on the second drum support. Thefirst and second drum supports are located a spaced distance apartbetween the first end and the second end of the drum. The drivemechanism may be located at any position relative to the first andsecond drum supports. However, preferably, the drive mechanism ispositioned between the first drum support and the second drum support.

Further, the first and second drum supports may be located at anypositions along the length of the drum between the first and second endswhich are capable of supporting the drum in the desired manner and whichpermit the proper functioning of the first and second drum load sensorsof the control system or the proper performance of the first and seconddrum load sensing steps of the controlling method. However, preferably,the first drum support is located between the first end of the drum anda midpoint of the drum, and wherein the second drum support is locatedbetween the second end of the drum and the midpoint of the drum.

In the controlling method, the method includes a number of sensing stepsin order to obtain input data for the controlling step such that theinput data is utilized to adjust or control the rotation speed of thedrum and the feedrate of the oil sand feed mechanism in order to producea desired solid stream and a desired liquid stream. The sensing stepsmay be performed in any suitable manner and by any suitable mechanism ordevice capable of sensing the desired parameter and providing theresulting data for performance of the controlling step. However,preferably, the controlling method is performed utilizing the controlsystem of the invention. Thus, the sensing steps are performed utilizingthe sensors of the control system.

Thus, the control system includes a number of sensors which provideinput data to the controller, whereby the controller utilizes the inputdata to adjust or control the rotation speed of the drum and thefeedrate of the oil sand feed mechanism in order to produce a desiredsolid stream and a desired liquid stream. Any conventional sensors orsensing apparatuses or devices may be utilized which are capable of, andsuitable for, sensing the desired parameter and providing the desiredinput data.

Accordingly, the controlling method includes the step of sensing thefirst drum load exerted on the first drum support. In the controlsystem, a first drum load sensor is associated with the first drumsupport for sensing the first drum load exerted on the first drumsupport.

Further, the controlling method includes the step of sensing the seconddrum load exerted on the second drum support. Similarly, in the controlsystem, a second drum load sensor is associated with the second drumsupport for sensing the second drum load exerted on the second drumsupport.

As well, the controlling method includes the step of sensing thefeedrate of the oil sand feed mechanism. In the control system, an oilsand feedrate sensor is associated with the oil sand feed mechanism forsensing the feedrate of the oil sand feedrate mechanism.

Finally, the controlling method includes the step of controlling therotation speed of the drum and the feedrate of the oil sand feedmechanism in response to input data from the first drum load sensingstep, the second drum load sensing step and the feedrate sensing step.In the control system, the controller is operatively connected with thefirst drum load sensor, the second drum load sensor, the oil sandfeedrate sensor, the drive mechanism and the oil sand feed mechanism.Thus, in response to the input data from each of the first drum loadsensor, the second drum load sensor and the oil sand feedrate sensor,the controller may adjust one or both of the drum rotation speed and theoil sand feed mechanism feedrate.

Both the controlling step and the controller control or adjust one orboth of the rotation speed of the drum and the feedrate of the oil sandfeed mechanism in order to maintain or achieve desired properties ofboth the solid stream and the liquid stream. More particularly, adensity of the solid stream at the solid stream outlet is preferablymaintained at or above a minimum design density. In addition, aconcentration of the solid particles in the liquid stream is maintainedat or below a maximum design concentration.

In other words, the drum rotation speed and the feed rate are adjustedsuch that a desired amount or percentage of the solid particles in theoil sand comprise the solid stream and are being discharged at the solidstream outlet, rather than comprising the liquid stream and beingdischarged at the liquid stream outlet. However, a balance is requiredto be achieved between the density of the solid stream and theconcentration of the solid particles in the liquid stream. Inparticular, it has been found that an increase in the density of thesolid stream greater than a desired maximum density will result in anundesirable increase in the concentration of the solid particles in theliquid stream.

Thus, in the controlling method, the controlling step is performed sothat a density of the solid stream at the solid stream outlet ismaintained at or above a minimum design density and so that aconcentration of the solid particles in the liquid stream is maintainedat or below a maximum design concentration. In the control system, thecontroller is configured so that a density of the solid stream at thesolid stream outlet is maintained at or above a minimum design densityand so that a concentration of the solid particles in the liquid streamis maintained at or below a maximum design concentration.

In order to operate the apparatus efficiently, the controlling step ispreferably performed so that the feedrate of the oil sand feed mechanismis maximized. Similarly, the controller is preferably configured tomaximize the feedrate of the oil sand feed mechanism. It has been foundthat the greater the feedrate of the oil sand, or the higher the solidsloading within the drum, the greater the bitumen recovery in the liquidstream. In this regard, it has been found that the residence time of theoil sand within the drum is not critical to the recovery of bitumenwithin the liquid stream.

Further, it has been found that the feed rate of the oil sand and therotation speed of the drum are proportional. Accordingly, if thefeedrate of the oil sand feed mechanism is increased, the drumrotational speed is required to be increased proportionately in orderfor the apparatus to operate in the desired manner and to permit thedrum to convey the oil sand therethrough for processing without anysignificant back-up of the oil sand in the drum.

Thus, to increase the feedrate, the rotation speed of the drum must bealso be increased. However, as the drum speed increases, the density ofthe solid stream at the solid stream outlet tends to decrease.Conversely, as the drum speed decreases, the density of the solid streamtends to increase. Thus, although it is desirable to maximize thefeedrate of the oil sand feed mechanism, a balance is required to beachieved between the feedrate of the oil sand feed mechanism and therotation speed of the drum in order to achieve a desired density of thesolid stream.

Further, as discussed above, the rotation speed of the drum must bemaintained at a speed which permits the drum to convey the oil sandthrough the drum in a desired manner for processing without anysignificant back-up of the oil sand in the drum.

For instance, in the preferred embodiment, the drum is comprised of aprocessing zone, wherein the spiral trough extends through theprocessing zone and wherein the spiral trough has a height through theprocessing zone. Preferably, the controller is configured so that theoil sand which passes through the processing zone is substantiallycontained in the spiral trough below the height of the spiral trough.Similarly, the controlling step is performed so that the oil sand whichpasses through the processing zone is substantially contained in thespiral trough below the height of the spiral trough. In other words, itis desirable that the oil sand be substantially contained within thespiral trough in order to enhance the processing of the oil sand withinthe processing zone and to minimize the amount or percentage of solidparticles moving within the liquid stream towards the first end of thedrum. Rather, the oil sand is processed and the solid particles aresubstantially moved by the spiral trough towards the second end of thedrum.

Further, in the preferred embodiment, the drum is comprised of acompressing zone, wherein the spiral trough extends through thecompressing zone and wherein the spiral trough has a height through thecompressing zone. Preferably, the controller is configured so that thesolid stream which passes through the compressing zone is substantiallycontained in the spiral trough below the height of the spiral trough.Similarly, the controlling step is preferably performed so that thesolid stream which passes through the compressing zone is substantiallycontained in the spiral trough below the height of the spiral trough. Inother words, it is again desirable that the solid stream besubstantially contained within the spiral trough in order to enhance thecompressing of the solid stream to expel any excess or residual watertherefrom while minimizing the amount or percentage of solid particlescontained within the water and forming a part of the liquid streamflowing towards the first end of the drum. Rather, the compressed solidparticles forming the solid stream are preferably substantially moved bythe spiral trough towards the second end of the drum.

Finally, as indicated, the drum rotation speed and feedrate controllingstep of the method is performed in response to input data from the firstdrum load sensing step, the second drum load sensing step and thefeedrate sensing step. Similarly, the controller of the control systemadjusts the drum rotation speed and the oil sand feed mechanism feedratein response to the input data from each of the first drum load sensor,the second drum load sensor and the oil sand feedrate sensor.

The oil sand feedrate sensor and the feedrate sensing step provide datarelating to the actual feedrate of the oil sand feed mechanism. Thefirst drum load sensor and the first drum load sensing step provide datarelating to the first drum load exerted on the first drum support. Thesecond drum load sensor and the second drum load sensing step providedata relating to the second drum load exerted on the second drumsupport. In operation, the apparatus provides a desired or optimumweight distribution between the first drum support and the second drumsupport. Thus, the controller or controlling step preferably adjusts thedrum rotation speed and the oil sand feedrate in response to a change ineither the first drum load or the second drum load.

In operation, an increase in the first drum load is typically indicativeof a back-up of the oil sand within the drum. Accordingly, the drumrotation speed and/or the oil sand feedrate may need to be adjusted toobtain a desired movement or flow of the oil sand and the solid streamwithin the drum. In particular, the drum rotation speed may be increasedand/or the oil sand feedrate may be decreased.

A decrease in the second drum load is typically indicative of a decreasein the density of the solid stream. Thus, assuming that the apparatus isoperating at parameters providing a desired or optimum density, adecrease in the second drum load will indicate a decrease in the densitybelow the desired or optimum solid stream density. Accordingly, the drumrotation speed and/or the oil sand feedrate may need to be adjusted toincrease the solid stream density. In particular, the drum rotationspeed may be decreased and/or the oil sand feedrate may be increased.

In practice, the desired or optimum density of the solid stream at thesolid stream outlet is predetermined and utilized as a “set point”during the operation of the apparatus. The “set point” is predeterminedtaking into account the desired minimum density of the solid stream andthe desired maximum concentration of the solid particles in the liquidstream. Further, the desired feedrate of the oil sand feed mechanism isalso selected taking into account the density set point. The rotationspeed of the drum is then adjusted during operation of the apparatus inresponse to a change in the first and second drum loads in order toachieve or maintain the density of the solid stream at the solid streamoutlet at the set point.

Thus, the controlling method and control system utilizes threeparameters in order to achieve the desired result, being the feedrate ofthe oil sand feed mechanism, the rotation speed of the drum and the drumloads exerted on the first and second drum supports.

SUMMARY OF DRAWINGS

Embodiments of the invention will now be described with reference to theaccompanying drawings, in which:

FIG. 1 is a side view of an embodiment of a separation apparatus shownin the prior art;

FIG. 2 is a longitudinal sectional view of the embodiment of theseparation apparatus of FIG. 1 shown in the prior art;

FIG. 3 is a side view of a preferred embodiment of an apparatus of theinvention comprising a drum and a screen section;

FIG. 4 is a longitudinal sectional view of the apparatus shown in FIG.3;

FIG. 5 is an end view of the apparatus shown in FIG. 3 from a first end;

FIG. 6 is a cross-sectional view of the apparatus taken along linesVI-VI of FIG. 4;

FIG. 7 is a side view of the apparatus shown in FIG. 3, furthercomprising a solid particle mixing section;

FIG. 8 is a longitudinal sectional view of the apparatus shown in FIG.7;

FIG. 9 is a cross-sectional view of the apparatus taken along linesIX-IX of FIG. 8; and

FIG. 10 is a schematic of a preferred embodiment of a control system ofthe invention for the apparatus shown in FIG. 3.

DETAILED DESCRIPTION

FIGS. 1-2 show a countercurrent separator vessel (12) as previouslyutilized in Canadian Patent No. 2,123,076 issued Nov. 17, 1998 to Strandet. al. in the performance of the method described therein. Referring toFIGS. 1 and 2, lumps of oil sand are fed to one end of thecountercurrent separator (12) via a conveyor line (10) which extendsinto the separator (12) at least far enough so that the oil sand can beguided to the start of a spiral ribbon (18) associated with theseparator (12). Warm water is fed to the opposite end of the separator(12) via a warm water line (14).

The separator (12) comprises a drum (20) which is mounted on rollers(22) for rotation about a horizontal axis, and which is driven by drivemeans well known in the art. The spiral ribbon (18) is fixed to theinside of the drum (20) and includes a number of separate flights. Alsoassociated with the drum (20) are a number of lifters (24) which consistof flat blades mounted on the interior of the drum (20) essentiallyperpendicular to the flights of the spiral ribbon (18). The height ofthe spiral ribbon (18) is the same throughout the length of the drum(20). Further, the height of the lifters (24) corresponds with theheight of the spiral ribbon (18) such that the height of the lifters(24) is also the same throughout the length of the drum (20). Finally,the distance between the flights of the spiral ribbon (18), which mayalso be referred to as either the width of the spiral ribbon (18) or thepitch of the spiral ribbon (18), is also the same throughout the lengthof the drum (20).

The separator (12) is equipped with a warm water discharge opening (26)from which warm water containing bitumen and dispersed fine material arewithdrawn from the separator (12), which warm water discharge opening(26) is at the opposite end of the separator (12) from the warm waterline (14). The separator (12) also has a solid material dischargeopening (27) at the opposite end of the separator (12) from the conveyorline (10), and which is fed by a number of draining pockets (28), whichlift the solid material out of the bath to partially drain it beforedischarging the solid material from the separator (12). Finally, theseparator (12) is also equipped with a settling zone (30) adjacent thewarm water discharge opening (26) which permits solid material to settleto the bottom of the separator (12) before the warm water exits theseparator (12).

Referring to FIGS. 3-10, the present invention relates to an apparatus(32) for processing oil sand to produce a liquid stream (34) comprisingwater and bitumen and a solid stream (36) comprising solid particles, acontrol system (38) for the apparatus (32) and a method for controllingthe apparatus (32). In the preferred embodiment, the apparatus (32) isintended to be used in substitution for the countercurrent separatorvessel (12).

Further, in the preferred embodiment, the apparatus (32) is intended tobe used in the performance of the oil sand extraction process asdescribed and shown in the flow chart of FIG. 1 of Canadian Patent No.2,123,076 issued Nov. 17, 1998 to Strand et. al. In particular, theapparatus (32) as shown in FIG. 3 herein may be used to perform thefunctions of the vessel (12) described in Canadian Patent No. 2,123,076.Further, the apparatus (32) as shown in FIG. 8 herein may be used toperform the functions of both the vessel (12) and the mixing drum ofCanadian Patent No. 2,123,076, wherein the mixing drum is referred to byreference numeral “36” and is particularly shown in FIG. 4 of CanadianPatent No. 2,123,076.

In the preferred embodiment, the oil sand is comprised of a matrix ofbitumen, solid particles and water. The bitumen is comprised of heavyoil or viscous hydrocarbons. The solid particles are comprised ofmineral matter including coarse mineral matter, such as sand and rock,and fine mineral matter such as silt and clay. Thus, followingprocessing of the oil sand by the apparatus (32), the liquid stream (34)is produced which is comprised of water and bitumen and which may alsobe referred to as a “bitumen froth.” The liquid stream (34) may alsoinclude an amount of fine mineral matter which is not able to beseparated from the bitumen during the processing of the oil sand.Further, the solid stream (36) is produced by the apparatus (32) whichis comprised of solid particles including both fine and course mineralmatter.

Thus, the oil sand entering the apparatus (32) is comprised of an amountor percentage of solid particles. Preferably, a greater amount orpercentage of those solid particles exits through the solid stream (36)as compared with the liquid stream (34). More particularly, the amountor percentage of the solid particles comprising the solid stream (36) ismaximized, while the amount or percentage of the solid particlescomprising the liquid stream (34) is minimized. In the preferredembodiment, based upon the assumptions that the oil sand entering theapparatus (32) is comprised of 100% of the solid particles and that anamount of water will be lost during processing by the apparatus (32),the solid stream (36) exiting the apparatus (32) is typically comprisedof between about 85-90% of the solid particles. Conversely, the liquidstream (34) exiting the apparatus (32) is typically comprised of betweenabout 70-80% water, between about 10-15% bitumen and between about10-15% of the solid particles.

Referring to FIGS. 3-9, the apparatus (32) is comprised of a generallycylindrical drum (40) having a first end (42) and an opposed second end(44), and further having an exterior surface (46) and an interiorsurface (48). The drum (40) may include a drain (not shown) if desiredfor maintenance purposes. Further, the drum (40) is preferably mountedwith a platform (50) such that the drum (40) is rotatable about alongitudinal axis extending between the first and second ends (42, 44).The drum (40) may be rotatably mounted with the platform (50) by anysupport structure or support mechanism permitting the rotation of thedrum (40) about its longitudinal axis. However, in the preferredembodiment, the apparatus (32) is comprised of a first drum support (52)for supporting the drum (40) and a second drum support (54) forsupporting the drum (40). Preferably, each of the first and second drumsupports (52, 54) is comprised of one or more rollers (56) such that thedrum (40) is rotatably supported thereby.

Further, the apparatus 32) is comprised of a drive mechanism (58) whichis operably connected or mounted with the drum (40) for rotating thedrum (40) about its longitudinal axis while supported by the first andsecond drum supports (52, 54). Any conventional or known drive mechanismmay be used which is capable of rotating the drum (40) at a desiredrotation speed. In the preferred embodiment, the drive mechanism (58) isassociated with the exterior surface (46) of the drum (40). Forinstance, as shown in FIG. 3, a drive motor and gear system may beutilized to drive a gear operatively engaged or mounted about theexterior surface (46) of the drum (40).

The drum (40) is mounted with the platform (50) and rotatably supportedby the first and second drum supports (52, 54) such that a desiredweight distribution between the supports (52, 54) is achieved. Thus, afirst drum load is exerted on the first drum support (52), while asecond drum load is exerted on the second drum support (54). Todistribute the drum load or weight of the drum (40), the first andsecond drum supports (52, 54) are a spaced apart along a length of thedrum (40) between the first end (42) and the second end (44) of the drum(40). Further, the drive mechanism (58) is preferably positioned betweenthe first and second drum supports (52, 54). More preferably, the firstdrum support (52) is located between the first end (42) of the drum (40)and a midpoint of the drum (40). Further, the second drum support (54)is located between the second end (44) of the drum (40) and the midpointof the drum (40). The midpoint of the drum (40) is about the middle ofthe drum (40) longitudinally or about equidistant between the first andsecond ends (42, 44).

Further, as described further below, the control system (38) includes afirst drum load sensor (60) and a second drum load sensor (62). Anyknown or conventional load sensors or load cells may be utilized whichare compatible with and suitable for sensing the necessary drum load.Preferably, the first drum load sensor (60) is associated with the firstdrum support (52) for sensing the first drum load. Similarly, the seconddrum load sensor (62) is associated with the second drum support (54)for sensing the second drum load.

In addition, the drum (40) is preferably comprised of a conditioningzone (64) adjacent to the first end (42), a compressing zone (66)adjacent to the second end (44), and a processing zone (68) between theconditioning zone (64) and the compressing zone (66). As describedfurther below, each of the zones is provided for performing a differentfunction as the oil sand passes through the drum (40) from the first end(42) towards the second end (44).

As well, the apparatus (32) is comprised of a rotatable spiral trough(70) which extends along the interior surface (48) of the drum (40).Preferably, the spiral trough (70) is fixed to the interior surface (48)of the drum (40) so that rotation of the drum (40) by the drivemechanism (58) rotates the spiral trough (70). The spiral trough (70) isprovided for imparting a spiral rolling motion to the oil sand withinthe drum (40). Preferably, the spiral trough (70) extends through eachof the conditioning zone (64), the processing zone (68) and thecompressing zone (66).

The spiral trough (70) may extend along the interior surface (48) of thedrum (40) for any total number of revolutions, through each of the zones(64, 68, 66), which is capable of performing the intended functions ofeach of the conditioning, processing and compressing zones (64, 68, 66).Preferably, the spiral trough (70) extends along the interior surface(48) of the drum (40), and through each of the zones (64, 68, 66), for atotal of between about five and twenty revolutions of the drum (40). Inthe preferred embodiment, the spiral trough (70) extends for a total ofabout fourteen revolutions of the drum (40) through each of the zones(64, 68, 66).

The number of revolutions of the spiral trough (70) in each of the zones(64, 68, 66) may also vary depending upon the function or purpose beingperformed by the respective zone. In the preferred embodiment, theconditioning zone (64) includes about three revolutions of the drum(40), the processing zone (68) includes about 8 revolutions of the drum(40) and the compressing zone (66) includes about three revolutions ofthe drum (40).

In order to facilitate or enhance the spiral rolling motion imparted tothe oil sand by the spiral trough (70), the apparatus (32) preferablyfurther includes a plurality of lifting members (72) or lifters forlifting the oil sand as the spiral trough (70) rotates. The liftingmembers (72) are preferably oriented generally transversely within andspaced along the spiral trough (70). Thus, the lifting members (72) arealigned longitudinally, or along the longitudinal axis of the drum (40),and radially about the drum (40).

The lifting members (72) may be spaced along the spiral trough (70) atany distance apart, or may be distributed about the circumference of theinterior surface (48) of the drum (40) at any intervals, permitting thelifting member (72) to perform its function. Preferably, the liftingmembers (72) are distributed at least about every 90 degrees about thecircumference of the interior surface (48) of the drum (40). However, ithas been found that if the lifting members (72) are distributed in amanner permitting the lifting members (72) to “line up” that the drivemechanism (58), and in particular the drive motor, may experienceundesirable surge loading. Thus, in the preferred embodiment, thelifting members (72) are distributed about every 55 degrees, as shown byreference “A” in FIG. 6, about the circumference of the interior surface(48) through each of the conditioning, processing and compressing zones(64, 68, 66).

Further, the apparatus (32) includes a number of inlets and outlets forproviding the desired countercurrent separation of the oil sand withinthe drum (40). In particular, the apparatus (32) is comprised of an oilsand inlet (74) for supplying the oil sand feedstock or raw oil sand tothe drum (40). Prior to supplying the oil sand to the drum (40), the oilsand may be prepared by breaking the lumps of oil sand into a desirablesize compatible for processing by the apparatus (32). For instance, theoil sand may be first subjected to a conventional oil sand feederbreaker or other size limiting device as described in Canadian PatentNo. 2,123,076.

Preferably, the oil sand inlet (74) communicates with the conditioningzone (64) of the drum (40). Although the oil sand inlet (74) maycommunicate with the conditioning zone (64) in any manner, preferably,the oil sand inlet (74) extends through the first end (42) of the drum(40) to a location adjacent the conditioning zone (64). More preferably,the oil sand inlet (74) extends to the first revolution of the spiraltrough (70), nearest the first end (42) of the drum, which comprises theconditioning zone (64). This preferred location of the oil sand inlet(74) is intended to maximize the exposure of the oil sand to theconditioning zone (64) by increasing the length or portion of theconditioning zone (64) to which the oil sand is exposed as it movestowards the second end (44) of the drum (40).

Further, the oil sand inlet (74) may be comprised of any suitableconduit, pipe or conveyance device capable of conveying or transportingthe oil sand to the conditioning zone (64). However, preferably, the oilsand inlet (74) is comprised of an apron feeder. Further, referring toFIG. 10, the oil sand inlet (74) is associated with an oil sand feedmechanism (73) for feeding or supplying the oil sand at a desiredfeedrate to the oil sand inlet (74). The oil sand feed mechanism (73)may be any solids conveyor or feed mechanism or device capable ofconveying the oil sand feedstock to the oil sand inlet (74) at a desiredfeedrate.

As well, the control system (38) includes an oil sand feedrate sensor(75), as shown in FIG. 10. Any known or conventional sensor may be usedwhich is compatible with and suitable for sensing the feedrate of theoil sand to the oil sand inlet (74). Thus, the oil sand feedrate sensor(75) is preferably associated with the oil sand feed mechanism (73) forsensing the feedrate of the oil sand feedrate mechanism (73).

As well, the apparatus (32) is comprised of a liquid stream outlet (76)for the drum (42). Preferably, the liquid stream outlet (76) is alsolocated at or adjacent the first end (42) of the drum (40). The liquidstream outlet (76) is provided for discharging the liquid stream (34)from the drum (40) or for conducting the liquid stream (34) out of thedrum (40) for further processing. For instance, as described furtherbelow, the liquid stream (34) may be further processed to provide anamount of water for recycling to the drum (40) and/or to provide anamount of a sludge for return to the apparatus (32).

Further, the liquid stream outlet (76) may be comprised of any suitableconduit, pipe or discharge device capable of discharging or expellingthe liquid stream (34) from the drum (40). However, preferably, theliquid stream outlet (76) is comprised of the first end (42) of the drum(40) defining a discharge opening which is sized and positioned toprovide a gradient such that the flow of the liquid stream (34) towardsthe liquid stream outlet (76), and the discharge of the liquid stream(34) from the liquid stream outlet (76), are facilitated thereby.

The apparatus (32) is further comprised of a water inlet (78) forsupplying water to the drum (40). Preferably, the water inlet (78)communicates with the processing zone (68) of the drum (40). Althoughthe water inlet (78) may communicate with the processing zone (68) inany manner, preferably, the water inlet (78) extends through the secondend (44) of the drum (40) to a location within the processing zone (68).More preferably, the water inlet (78) extends to a location within theprocessing zone (68) adjacent or in proximity to the last or finalrevolution of the spiral trough (70), nearest to the second end (44) ofthe drum (40), which comprises the processing zone (68).

More particularly, the spiral trough (70) through the processing zone(68) preferably defines a processing zone inlet (80), nearer the firstend (42) of the drum (40), and a processing zone outlet (82), nearer thesecond end (44) of the drum (40). In the preferred embodiment, the waterinlet (78) communicates with the processing zone (68) at a locationadjacent to the processing zone outlet (82). This preferred location ofthe water inlet (78) is intended to maximize the exposure of the oilsand to the water within the drum (40) by increasing the length orportion of the processing zone (68) which is exposed to the water as thewater flows from the water inlet (78) towards the first end (42) of thedrum (40).

Further, as discussed below, the water is heated prior to beingconducted through the water inlet (78) and is at its highest temperatureas it enters through the water inlet (78). Thus, as a result of thepositioning of the water inlet (78), the oil sand first entering thedrum (40) through the oil sand inlet (74) is contacted with the water atits lowest temperature just before the water exits through the liquidstream outlet (76). Conversely, the oil sand is contacted with the waterat its highest temperature adjacent to the processing zone outlet (82),prior to removal of the solid stream (36). In effect, the bitumen thatis most difficult to liberate is contacted with the highest temperatureof water, thus facilitating its liberation.

Preferably, a sufficient amount of water is conducted through the waterinlet (78) to ensure a gradient through the drum (40) towards the firstend (42) of the drum (40). Thus, the liquid stream (34) will tend toflow towards the liquid stream outlet (76) at the first end (42). In thepreferred embodiment, a sufficient water gradient is created so long asabout 5-6 inches (about 12.7-15.24 cm) of water are provided above thesolid particles contained therein.

Further, the water inlet (78) may be comprised of one or more of anysuitable conduit, pipe or tubular member capable of conducting orconveying the water to the processing zone (68). However, preferably,the water inlet (78) is comprised of two water distribution lines. Afirst water distribution line (84) provides an amount of water recycledfrom the liquid stream (34) discharged from the liquid stream outlet(76). A second water distribution line (86) provides an additionalamount of water supplied from a secondary water supply or reservoir.

As indicated previously, the liquid stream (34) may be further processedto provide an amount of water for recycling and/or to provide an amountof a sludge for return to the apparatus (32). In particular, the liquidstream (34) may be further processed for separation of the bitumen froma suspension of dispersed fine solid particles. For instance, one ormore of a froth separator vessel (not shown), a froth flotation cell(not shown), a froth cleaner vessel (not shown) and a solids thickener(not shown), as described in Canadian Patent No. 2,123,076, may be usedto perform this function. In essence, the bitumen is substantiallyremoved from the suspension of dispersed fine solid particles. Thesuspension is then dewatered to remove an amount of water for recyclingto the drum (40) via the first water distribution line (84) and toproduce an amount of a sludge.

The sludge comprises a suspension of dispersed fine solid particles,typically dispersed fine mineral matter consisting of clays and silts. Asmall amount of coarse material may also be present in the sludge, asmay be a small amount of bitumen not able to be separated from the solidparticles during processing.

The amount of water available for recycling to the drum (40) via thefirst water distribution line (84) may not be sufficient to meet theneeds of the apparatus (32) or the process performed therein. Thus,where required, an additional amount of water, referred to as makeupwater, may be supplied from a secondary water supply or reservoir viathe second water distribution line (86) in order to supply or meet thetotal water demand or requirements of the apparatus (32). The watersupplied by each of the first and second water distribution lines (84,86) is heated in a known or conventional manner prior to introductioninto the drum (40) in order to facilitate or enhance the separation ofthe bitumen from the solid particles.

As well, the apparatus (32) is further comprised of a solid streamoutlet (88) for the drum (40). Preferably, the solid stream outlet (88)is located at or adjacent the second end (44) of the drum (40) such thatthe compressing zone (66) is located between the processing zone (68)and the solid stream outlet (88). The solid stream outlet (88) isprovided for discharging the solid stream (36) from the drum (40) or forconveying the solid stream (36) out of the drum (40) for furtherprocessing. In the preferred embodiment, as described further below, thesolid stream (36) is subsequently vacuum filtered to remove any residualwater from the solid particles.

Thus, the apparatus (32) provides for countercurrent separation of theoil sand. Specifically, the oil sand is introduced to the first end (42)of the drum (40) and transported through the drum (40) towards thesecond end (44) by the action of the spiral trough (70), where thesolids stream is discharged through the solid stream outlet (88). Wateris introduced through the water inlet (78) to the processing zone (68)adjacent the second end (44) of the drum (40) and flows in the directionof the first end (42), where the liquid stream (34) is discharged orexpelled through the liquid stream outlet (76).

Each of the conditioning zone (64), the processing zone (68) and thecompressing zone (66) perform a particular function as the oil sand ismoved therethrough by the action of the spiral trough (70).

The conditioning zone (64) permits the oil sand to be introduced to andgently contacted by the water in order to commence the liberation orseparation of the bitumen from the oil sand. Preferably, theconditioning zone (64) defines a conditioning zone inlet (90) and aconditioning outlet (92) adjacent the processing zone inlet (80). Theoil sand inlet (74) preferably communicates with the conditioning zoneinlet (90). Further, in the preferred embodiment, it has been found thatat the conditioning zone inlet (90), the solid stream (36) in the drum(40) includes about 48% solid particles and about 52% water and bitumen.

The processing zone (68) agitates the oil sand within the spiral trough(70) and further contacts the oil sand with the water in order toenhance the extraction or liberation of the bitumen, while alsoexpelling some of the water from the solid stream (36) moving towardsthe second end (44) of the drum (40). In the preferred embodiment, ithas been found that at the processing zone inlet (80), the solid stream(36) in the drum (40) includes about 55% solid particles and about 45%water and bitumen. At the processing zone outlet (82), the solid stream(36) in the drum (40) includes about 53% solid particles and about 47%water and bitumen. The increased water content near the processing zoneoutlet (82) is largely a result of the positioning of the water inlet(78) therein.

The compressing zone (66) compresses the oil sand or solid stream (36)within the spiral trough (70) moving towards the second end (44) of thedrum (40) to expel any excess or residual water prior to dischargethrough the solid stream outlet (88). Preferably, the compressing zone(66) defines a compressing zone inlet (94) adjacent the processing zoneoutlet (82) and a compressing zone outlet (96). In the preferredembodiment, it has been found that at the compressing zone inlet (94),the solid stream (36) in the drum (40) includes about 53% solidparticles and about 47% water and bitumen. At the compressing zoneoutlet (96), the solid stream (36) in the drum (40) includes about 70%solid particles and about 30% water and bitumen.

Each of the conditioning, processing and compressing zones (64, 68, 66)is configured or adapted to perform its respective function. Moreparticularly, the spiral trough (70) through each zone (64, 68, 66) hasa width (98) or pitch and a height (100). In combination, the selectionof the width (98) and the height (100) provide a transversecross-sectional area of the spiral trough (70). In the preferredembodiment, the width (98), the height (100) and the resultingcross-sectional area of the spiral trough (70) in each of theconditioning, processing and compressing zones (64, 68, 66) is selectedto facilitate or enhance the intended function of that respective zone(64, 68, 66).

With respect to the width (98) of the spiral trough (70), the width (98)or pitch generally decreases through each of the conditioning,processing and compressing zones (64, 68, 66) to expel or squeeze thewater from the solid stream (36) in the direction of the second end (44)of the drum (40).

Thus, preferably, the width (98) of the spiral trough (70) through thecompressing zone (66) is less than the width (98) of the spiral trough(70) through the processing zone (68). Further, the width (98) of thespiral trough (70) at the compressing zone outlet (96) is preferablyless than the width (98) of the spiral trough (70) at the compressingzone inlet (94). Similarly, the width (98) of the spiral trough (70)through the processing zone (68) is less than the width of the spiraltrough (70) through the conditioning zone (64).

Within the processing zone (68), the width (98) of the spiral trough(70) is selected, at least in part, to substantially retain the solidparticles within the spiral trough (70) while accommodating the waterentering the processing zone (68) adjacent the processing zone outlet(82) and maintaining the desired water gradient. Thus, the flow of anysolid particles within the water towards the first end (42) of the drum(40) may be minimized. In the preferred embodiment, the processing zone(68) includes 8 revolutions of the spiral trough (70), each having awidth (98) of about 0.748 meters.

Within the compressing zone (66), the width (98) of the spiral trough(70) is selected, at least in part, to compress the oil sand or solidstream (36) within the spiral trough (70) to expel the water from thesolid particles. However, the width (98) is also selected with regard tothe anticipated amount of solid particles to be contained or movedwithin the spiral trough (70) and the anticipated size of the solidparticles such that the spiral trough (70) is able to accommodate thesolid particles therein. Further, in the direction from the compressingzone inlet (94) towards the compressing zone outlet (96), the solidstream (36) is increasingly compressed or gradually further compressedby the spiral trough (70) to further expel the water. In the preferredembodiment, the compressing zone (66) includes 3 revolutions of thespiral trough (70), wherein the first revolution adjacent thecompressing zone inlet (94) has a width (98) of about 0.526 meters andthe remaining two revolutions of the spiral trough (70) have a width(98) of about 0.432 meters.

Within the conditioning zone (64), the width (98) of the spiral trough(70) is selected, at least in part, to accommodate the amount of oilsand entering the conditioning zone (64) such that the spiral trough(70) is able to substantially accommodate the oil sand therein whilemaintaining the desired water gradient. Further, the width (98) isselected to enhance the contact between the water and the oil sand. Inthe preferred embodiment, the conditioning zone (64) includes 3revolutions of the spiral trough (70), each having a width (98) of about0.943 meters.

With respect to the height (100) of the spiral trough (70), the height(100) generally increases through each of the conditioning, processingand compressing zones (64, 68, 66) to facilitate the desired watergradient through the drum (40) and to facilitate the flow of the liquidstream in the direction of the first end (42) of the drum (40).

Thus, preferably, the height (100) of the spiral trough (70) through atleast a portion of the compressing zone (66) is greater than the height(100) of the spiral trough (70) through both the conditioning zone (64)and the processing zone (68). Further, the height (100) of the spiraltrough (70) at the compressing zone outlet (96) is preferably greaterthan the height (100) of the spiral trough (70) at the compressing zoneinlet (94).

Within the compressing zone (66), the height (100) of the spiral trough(70) is selected, at least in part, to facilitate the desired watergradient through the drum (40) and to inhibit or prevent the undesirablebackflow of the liquid stream (34) towards the second end (44) of thedrum (40). Further, the height (100) of the spiral trough (70) in thecompressing zone (66) is also selected, in combination with the width(98), having regard to the anticipated amount of solid particles to beretained within the spiral trough (70) such that the spiral trough (70)is able to accommodate the solid particles therein.

Finally, the increased height of the spiral trough (70) from thecompressing zone inlet (94) to the compressing zone outlet (96) furtherinhibits any undesirable backflow of the liquid stream (34). As well,due to the decreasing width (98) of the spiral trough (70), the height(100) of the spiral trough (70) is preferably increased in the directionof the compressing zone outlet (96) so that the solid stream (36) may beaccommodated therein.

The preferred embodiment depicted in the Figures is a very smallcommercial scale apparatus (32) which is designed to be suitable forprocessing approximately 300 tonnes of oil sand per hour with aresidence time in the drum (40) of approximately 10 minutes. It iscontemplated that smaller or larger apparatus may be designed andconstructed by appropriate scaling of the design of the depictedpreferred embodiment. The dimensions of the preferred embodiment aretherefore exemplary only.

In the preferred embodiment, the conditioning, processing andcompressing zones (64, 68, 66) include a total of 14 revolutions of thespiral trough (70), numbered from the first end (42) in the direction ofthe second end (44) of the drum (40). The initial starting revolution(i.e. revolution no. 0) and revolutions no. 1 through no. 9 have aheight (100) of about 1.6 meters. Thus, the height (100) of the spiraltrough (70) through the conditioning zone (64) is 1.6 meters.

Revolutions no. 10 and no. 11 of the spiral trough (70) have a height(100) of about 1.7 meters and about 1.8 meters respectively. Thus, theheight (100) of the spiral trough (70) at the processing zone inlet (80)is about 1.6 meters, which increases to about 1.8 meters at theprocessing zone outlet (82).

Revolution no. 12 and no. 13 of the spiral trough (70) have a height(100) of about 1.9 meters, while revolution no. 14 reduces from a heightof about 1.9 meters to about 0.0762 meters. Thus, the height (100) ofthe spiral trough (70) at the compressing zone inlet (90) is about 1.8meters, which increases towards the compressing zone outlet (92) toabout 1.9 meters.

Finally, as discussed, the width (98) and the height (100) of the spiraltrough (70) in each zone (64, 68, 66) are selected in combination, orhaving regard to the other, such that the zone (64, 68, 66) has atransverse cross-sectional area which is compatible with the intendedfunction of that zone (64, 68, 66). In the preferred embodiment, thetransverse cross-sectional area of the spiral trough (70) through thecompressing zone (66) is less than the transverse cross-sectional areaof the spiral trough (66) through the processing zone (68).

Further, the liquid stream outlet (76) also has a height (102). Theheight (102) of the liquid stream outlet (76) is selected, at least inpart, to also facilitate the desired water gradient and the flow of theliquid stream (34) towards the liquid stream outlet (76). Thus,preferably, the height (100) of the spiral trough (70) through at leasta portion of the compressing zone (66) is greater than the height (102)of the liquid stream outlet (76). In the preferred embodiment, theheight (102) of the liquid stream outlet (76) is about 1.6 meters.

The lifting members (72) through the spiral trough (70) are alsoconfigured and spaced in each of the conditioning, processing andcompressing zones (64, 68, 66) of the drum (40) to lift the oil sand asthe spiral trough (70) rotates and to otherwise facilitate or assisteach zone (64, 68, 66) in the performance of its respective intendedfunction.

Thus, each lifting member (72) has a height (104) as shown by the dottedlines in FIGS. 4 and 8, wherein the height (104) may vary through eachof the conditioning, processing and compressing zones (64, 68, 66) asnecessary to facilitate or enhance the intended function of therespective zone (64, 68, 66) as discussed above.

Within the processing zone (68), the height (104) of the lifting members(72) is selected, at least in part, to contribute to the desiredagitation of the oil sand within the spiral trough (70) and contactbetween the oil sand and the water in order to enhance the extraction orliberation of the bitumen. Within the compressing zone (66), the height(104) of the lifting members (72) is selected, at least in part, to moveor convey the solid stream (36) in the direction of the second end (44)of the drum towards the solid stream outlet (88). Thus, less agitationof the oil sand is desirable within the compressing zone (66) ascompared with the processing zone (68).

Thus, the height (104) of the lifting members (72) through thecompressing zone (66) is preferably less than the height (104) of thelifting members (72) through the processing zone (68). In the preferredembodiment, the height (104) of the lifting members (72) in each of theconditioning zone (64) and the processing zone (68) is about 1.1 meters.The height (104) of the lifting members (72) in the compressing zone(66) is about 0.75 meters.

In addition, the drum (40) is preferably further comprised of a frothpooling section (106) as shown in FIGS. 4 and 8. The froth poolingsection (106) is preferably positioned adjacent the first end (42) ofthe drum, between the first end (42) and the conditioning zone (64), andin communication with the liquid stream outlet (76). The froth poolingsection (106) is provided for the settling of any solid particles in theliquid stream (34) to the bottom of the drum (40) prior to discharge ofthe liquid stream (34) through the liquid steam outlet (76). In otherwords, any solid particles that may be contained within, or that havebeen carried along by, the liquid stream (34) are provided with anopportunity to settle within the froth pooling section (106) in order toreduce or minimize the amount of solid particles within the liquidstream (34). In order to facilitate the settling of the solid particles,the spiral trough (70) does not extend through the froth pooling section(106).

The apparatus (32) may also be further comprised of a drum flocculantinlet (108) for introducing a flocculant to the oil sand within the drum(40). Preferably, the drum flocculant inlet (108) communicates with theprocessing zone (68) of the drum (40) so that the flocculant and thewater may together be gently mixed with the oil sand within theconditioning zone (64). More preferably, the drum flocculant inlet (108)communicates with the processing zone (68) adjacent to the water inlet(78) so that the flocculant may be mixed with the water beforecontacting the oil sand. The drum flocculant inlet (108) may also becombined with the water inlet (78) so that the drum flocculant inlet(108) is comprised of the water inlet (78). The flocculant aids orfacilitates the aggregation and settlement of the fine mineral mattercomprising the solid particles and may assist in increasing the recoveryof bitumen from the oil sand. Thus, the oil sand from the oil sand inlet(74) may be contacted and mixed with both the water and the flocculantwithin the conditioning zone (64).

In addition, the apparatus (32) may include a solid particle mixingsection (110). FIGS. 3-4 show the apparatus (32) without a solidparticle mixing section (110), while FIGS. 8-9 show the apparatus (32)with a solid particle mixing section (110). Where the apparatus 932)does not include a solid particle mixing section (110), the solid stream(36) from the apparatus (32) is preferably directed to a separate mixer(not shown) for further processing. For instance, the solid stream (36)may be directed to a mixing drum as described and shown in FIGS. 1 and 4of Canadian Patent No. 2,123,076.

Thus, referring to FIGS. 8-9, the solid particle mixing section (110) isprovided for mixing the solid particles contained within the drum (40)with at least one additive. Preferably, the solid particle mixingsection (110) is integral with the drum (40), such that the drum (40) iscomprised of the solid particle mixing section (110), and is locatedbetween the compressing zone (66) and the second end (44) of the drum(40). Preferably, the solid particle mixing section (110) defines amixing section inlet (109) and a mixing section outlet (111). Thus, themixing section inlet (109) is adjacent the compressing zone outlet (96)and the mixing section outlet (111) is adjacent the solid stream outlet(88). The solid particle mixing section (110) is positioned downstreamof the compressing zone (66) so that a significant or substantial amountof the water may be discharged or expelled from the solid particlesprior to further mixing of the solid particles with the desired additiveor additives.

Preferably, two additives are mixed with the solid stream (36) withinthe solid particles mixing section (110), being a flocculant and asludge. Any suitable flocculant may be used for further facilitating orpromoting the aggregation of any fine mineral matter or fine solidparticles comprising the solid stream (36). The sludge may be providedfrom any source. However, as described previously, the liquid stream(34) exiting the liquid stream outlet (76) may be further processed toproduce the sludge, which is then recycled back to the solid particlemixing section (110).

Preferably, each of the additives is introduced or communicated to thesolid particle mixing section (110) by a separate inlet, however, theadditives may be introduced concurrently by a single inlet. In thepreferred embodiment, the apparatus (32) is further comprised of amixing section sludge inlet (112) for introducing the sludge and amixing section flocculant inlet (114) for introducing the flocculant.Each of the inlets (112, 114) may be comprised of any suitable conduit,pipe or tubular member capable of conducting or conveying the sludge orflocculant respectively to the solid particle mixing section (110).

Further, the solid particle mixing section (110) preferably includes asludge inlet zone (116) and a flocculant inlet zone (118). In thepreferred embodiment, the flocculant inlet zone (118) is positionedadjacent the compressing zone outlet (96) and the sludge inlet zone(116) is located between the flocculant inlet zone (118) and the secondend (44) of the drum (40). The mixing section sludge inlet (112) extendsthrough the second end (44) of the drum (40) for communication with thesludge inlet zone (116), while the mixing section flocculant inlet (114)extends through the second end (44) of the drum (40) for communicationwith the flocculant inlet zone (118). Thus, the flocculant is introducedto, and mixed with, the solid particles prior to introducing and mixingthe sludge with the solid particles. This order of introduction ispreferred as it is believed that the flocculant coats the solidparticles, which then acts as a nucleus for the flocculation of thedispersed fine materials contained within the sludge.

Preferably, the spiral trough (70) extends through the solid particlemixing section (110) to impart a spiral rolling motion to the solidparticles within the solid particle mixing section (110) and therebyfacilitate or enhance the mixing of the flocculant and the sludge withthe solid particles. In the preferred embodiment, the length of the drum(40) is extended and the drum (40) comprises the solid particle mixingsection (110). Thus, as in the remainder of the drum (40), the spiraltrough (70) is fixed to the interior surface (48) of the drum (40)within the solid particle mixing section (110) so that rotation of thedrum (40) rotates the spiral trough (70) within the solid particlemixing section (110).

Preferably, the spiral trough (70) extends through the solid particlemixing section (110) for about 2 revolutions to facilitate mixing of thesolid particles and the flocculant and about 2 revolutions to facilitatemixing of the solid particles and flocculant with the sludge. In thepreferred embodiment, the solid particle mixing section (110) thereforeincludes about four revolutions of the spiral trough (70). However, thenumber of revolutions, as well the width (98), the height (100) and theresulting transverse cross-sectional area of the spiral trough (70)through the solid particle mixing section (110) are selected tofacilitate or enhance its intended function.

Within the solid particle mixing section (110), the width (98) of thespiral trough (70) is selected, at least in part, to accommodate thesize and amount of the solid particles entering the solid particlemixing section (110) from the compressing zone (66), as well as theamounts of the flocculant and the sludge being introduced therein. Thus,the width (98) of the spiral trough (70) through the solid particlemixing section (110) is preferably greater than the width (98) of thespiral trough (70) through the compressing zone (66). In the preferredembodiment, the width (98) of the spiral trough (70) through the solidparticle mixing section (110) is about 0.6 meters for the first tworevolutions and about 0.75 meters for the remaining two revolutions.

In addition, the height of the spiral trough (70) within the solidparticle mixing section (110) is selected, at least in part, to furtherinhibit or prevent the backflow of the liquid stream (34) from theprocessing zone (68) towards the solid particle mixing section (110) andalso to inhibit or prevent backflow from the solid particle mixingsection (110) to the compressing section (66). Additionally, as with thewidth (98), the height (100) is selected having regard to theanticipated amount of solid particles, flocculant and sludge to beconveyed through and mixed within the spiral trough (70). Preferably,the height (100) of the spiral trough (70) through the solid particlemixing section (110) is about the same as the maximum height (100) ofthe spiral trough (70) through the compressing zone (66). Thus, in thepreferred embodiment, the height of the spiral trough (70) through thesolid particle mixing section (110) is about 1.9 meters.

As well, the lifting members (72), as described previously, arepreferably continued along the spiral trough (72) through the solidparticle mixing section (110). The lifting members (72) are configured,sized and spaced in the solid particle mixing section (110) to lift thesolid particles as the spiral trough (70) rotates and to facilitate orenhance the intended function of the solid particle mixing section(110).

In the preferred embodiment, the lifting members (72) are distributedabout every 55 degrees about the circumference of the interior surface(48) of the drum (40) through the solid particle mixing section (110).Further, the height (104) of the lifting members (72), shown by thedotted line in FIG. 8, through the solid particle mixing section (110)is preferably greater than the height (104) of the lifting members (72)through the compressing zone (66) in order to enhance the mixing throughthe solid particle mixing section (110). Thus, in the preferredembodiment, the height (104) of the lifting members (72) in the solidparticle mixing section (110) is preferably greater than about 0.75meters and preferably between about 0.75 meters and about 1.1 meters.

Finally, the solid stream outlet (88) may be comprised of any suitableconduit, pipe or discharge device or conveyor capable of discharging orexpelling the solid stream (36) from the second end (44) of the drum(40). However, the solid stream outlet (88) is preferably as shown inFIGS. 3-4 and 7-8, wherein the solid particles comprising the solidstream (36) are sorted or separated according to the size of the solidparticle prior to being discharged.

Preferably, the solid stream outlet (88) is comprised of the drum (40)defining a plurality of perforations (120) at or adjacent the second(44) of the drum (40) which provide a screen section (122) of the drum(40). More particularly, where the apparatus (32) does not include thesolid particle mixing section (110), as shown in FIGS. 3-4, the screensection (122) is positioned adjacent the compressing zone outlet (96).Where the apparatus (32) includes the solid particle mixing section(110), as shown in FIGS. 8-9, the screen section (122) is positionedadjacent the mixing section outlet (111). The perforations (120) of thescreen section (122) are sized so that solid particles having a sizeless than or equal to a desired maximum size may exit the drum (40)through the perforations (120). In the preferred embodiment, the desiredmaximum size is about 75 millimeters, which for most applications willfacilitate pumping of the solid particles as a slurry after they haveexited the drum (40).

In addition, the solid stream outlet (88) is preferably furthercomprised of an oversized particle outlet (124) located at and definingthe second end (44) of the drum (40). Accordingly, solid particleshaving a size greater than the desired maximum size are conveyed throughthe screen section (122) for discharge from the drum (40) through theoversized particle outlet (124). The oversized particle outlet (124) ispreferably comprised of the second end (44) of the drum (40) defining anopening or conduit therein for passage of the oversized particles. Theoversized particles may be recombined with other solid particles or maybe directed to another location for disposal.

The drum (40) including the conditioning, processing and compressingzones (64, 68, 66), the screen section (122) and the solid particlemixing section (110) may have any relative dimensions so long as each iscapable of performing its intended function. However, in the preferredembodiment, the drum (40) including the conditioning, processing andcompressing zones (64, 68, 66) has a length, measured along thelongitudinal axis of the drum (40), of about 25 meters. The screensection (122) has a length of about 2.5 meters. Finally, the solidparticle mixing section (110) has a length of about 5 meters or twicelong as the screen section (122).

Further, it has been found that the residence time of the oil sandwithin the drum (40) is not particularly critical to the recovery ofbitumen within the liquid stream (34). Thus, where desired, the lengthof the drum (40) between the first and second ends (42, 44) may bereduced while maintaining the same number of revolutions of the spiraltrough (70) within the drum (40). In the preferred embodiment, theresidence time within the drum (40) is preferably between about 7 to 20minutes.

Preferably, the spiral trough (70), as described previously, extendsthrough the screen section (122) to the oversized particle outlet (124)to impart a spiral rolling motion to the solid particles within thescreen section (122). In the preferred embodiment, as in the remainderof the drum (40), the spiral trough (70) is fixed to the interiorsurface (48) of the drum (40) within the screen section (122) so thatrotation of the drum (40) rotates the spiral trough (70) within thescreen section (122).

The spiral rolling motion of the solid particles by the spiral trough(70) facilitates and enhances the sorting and exiting through theperforations (120) of those solid particles having a size less than orequal to the desired maximum size. Further, the action of the spiraltrough (70) also facilitates the exiting or discharge of the solidparticles having a size greater than the desired maximum size throughthe oversized particle outlet (124). However, in order to furtherfacilitate the sorting of the particles sizes and exiting through eitherthe screen section (122) or the oversized particle outlet (124), thelifting members (72) are not provided in the screen section (122).

The number of revolutions, as well the width (98), the height (100) andthe resulting transverse cross-sectional area of the spiral trough (70)through the screen section (122) are selected to facilitate or enhanceits intended function. Thus, within the screen section (122), the width(98) and the height (100) of the spiral trough (70) are selected, atleast in part, to be capable of conveying the solid particlestherethrough, while permitting the different sized particles to exitfrom either the perforations (120) of the screen section (122) or theoversized particle outlet (124).

Where there is no solid particle mixing section (110), as in FIGS. 3-4,the width (98) of the spiral trough (70) through the screen section(122) is preferably about the same as the width (98) of the spiraltrough (70) through at least a portion of the compressing zone (66). Theheight (100) of the spiral trough (70) through the screen section (122)is preferably less than the height (100) of the spiral trough (70)through the compressing zone (66) in order to facilitate the movement ofthe solid particles through the screen section (122).

Where there is a solid particle mixing section (110), as in FIGS. 8-9,the width (98) of the spiral trough (70) through the screen section(122) is less than the width (98) of the spiral trough (70) through thesolid particle mixing section (110). The height (100) of the spiraltrough (70) through the screen section (122) is preferably less than theheight (100) of the spiral trough (70) through the solid particle mixingsection (110) to again facilitate the movement of the solid particlesthrough the screen section (122).

In the preferred embodiment, either with or without the solid particlemixing section (110), the spiral trough (70) extends through the screensection (122) for about three revolutions of the drum (40). The width(98) of the spiral trough (70) through the screen section (122) is about0.5 meters. Further, the height (100) of the spiral trough (70) throughthe screen section (122) is about 0.0762 meters.

Where the apparatus (32) includes a solid particle mixing section (110),the solid stream (36) exiting through the solid stream outlet (88) ispreferably conveyed or discharged to a vacuum filter (not shown).Although any conventional vacuum filter may be used, the vacuum filteris preferably a vacuum belt filter as described in Canadian Patent No.2,123,076. In particular, the vacuum belt filter is comprised of aperforated belt which is covered by a filter media. The solid stream(36), being a mixture of solid particles, flocculant and sludge, isdeposited on the covered belt and a vacuum is drawn from underneath toremove water or moisture from the mixture. The dewatered mixture is thentransported for storage or disposal.

The subsequent dewatering of the solid stream (36) by the vacuum beltfilter may be facilitated or enhanced by the separation of the solidparticles according to size by the screen section (122) and theoversized particle outlet (124). In particular, the vacuum may work moreefficiently where the larger solid particles are deposited on top of thesmaller solid particles on the vacuum belt filter. Thus, the screensection (122) separates those solid particles having a size less than orequal to the desired maximum size. As these smaller solid particles exitthrough the perforations (120), the particles are preferably depositedupon the vacuum belt filter. The solid particles having a size greaterthan the desired maximum size are subsequently discharged through theoversized particle outlet (124). These larger solid particles may bedeposited upon the vacuum filter in a layer on top of or overlying thesmaller solid particles so that the smaller solid particles protect thevacuum filter surface from damage which might otherwise be caused by thelarger solid particles directly contacting the vacuum filter surface.Alternatively, the larger solid particles may be directed to a differentlocation for disposal.

As discussed, the invention also relates to the control system (38) forthe apparatus (32) and a method for controlling the apparatus (32). Thecontrol system (38) is comprised of the first drum load sensor (60), thesecond drum load sensor (62), the oil sand feedrate sensor (75) and acontroller (126). The controller (126) is operatively connected with thefirst drum load sensor (60), the second drum load sensor (62), the oilsand feedrate sensor (75), the drive mechanism (58) and the oil sandfeed mechanism (73). Thus, the controller (126) may control or adjustthe rotation speed of the drum (40) and the feedrate of the oil sandfeed mechanism (73) in response to input data from the first drum loadsensor (60), the second drum load sensor (62) and the oil sand feedratesensor (75). The preferred embodiment of the controlling method isperformed utilizing the control system (38) described herein.

The method for controlling the apparatus (32) is comprised of the stepof sensing the first drum load. Preferably, the first drum load sensingstep is performed using the first drum load sensor (60). The sensed datarelating to the first drum load is then communicated to the controller(126).

The method is further comprised of the step of sensing the second drumload. Preferably, the second drum load sensing step is performed usingthe second drum load sensor (62). The sensed data relating to the seconddrum load is also communicated to the controller (126).

In addition, the method is comprised of the step of sensing the feedrateof the oil sand feed mechanism (73). Preferably, the feedrate sensingstep is performed using the oil sand feedrate sensor (75) associatedwith the oil sand feed mechanism (73). The sensed data is furthercommunicated to the controller (126).

Finally, the method is comprised of the step of controlling the rotationspeed of the drum (40) and the feedrate of the oil sand feed mechanism(73). Preferably, the controlling step is performed using the controller(126). The controlling step is performed to adjust the rotation speedand feedrate in response to the sensed data from each of the sensingsteps. Thus, the sensed data from the first drum load sensor (60), thesecond drum load sensor (62) and the oil sand feedrate sensor (75) iscorrelated and any necessary adjustments are made to the rotation speedand feedrate in order to maintain or achieve desired properties of boththe solid stream (36) and the liquid stream (34).

More particularly, a minimum design density is determined for the solidstream (36) at the solid stream outlet (88). Further, a correlatingmaximum design concentration is preferably determined for the solidparticles in the liquid stream (34). Based upon the sensed data provideto the controller (126), one or both of the rotation speed of the drum(40) and the feedrate of the oil sand feed mechanism (73) may beincreased or decreased in order that the density of the solid stream(36) at the solid stream outlet (88) is maintained at or above theminimum design density and in order that the concentration of the solidparticles in the liquid stream (34) is maintained at or below themaximum design concentration.

Thus, the drum rotation speed and the feed rate are adjusted in order tomaintain a desired balance between the density of the solid stream (36)and the concentration of the solid particles in the liquid stream (34).In this regard, it has been found that an increase in the density of thesolid stream (36) greater than a desired maximum density will result inan undesirable increase in the concentration of the solid particles inthe liquid stream (34).

Further, in order to maximize the efficiency of the apparatus (32), thefeedrate of the oil sand feed mechanism (73) is preferably maximizedwhile still achieving the design density and concentration of the solidand liquid streams respectively. In particular, it has been found thatthe greater the oil sand feedrate, the higher the solids loading withinthe drum (40). The higher the solids loading in the drum (40), thegreater the bitumen recovery in the liquid stream (34). Further, it hasbeen found that the residence time of the oil sand within the drum (40)is not particularly critical to the recovery of bitumen within theliquid stream (34).

In addition, the rotation speed of the drum (40) must be maintained at aspeed which permits the drum (40) to convey the oil sand through thedrum (40) in a desired manner for processing without any significantback-up of the oil sand at the oil sand inlet (74) and in order that thesolid stream (36) within the drum (40) is substantially contained withinthe spiral trough (70) of each of the conditioning, processing andcompressing zones (64, 68, 66).

For instance, it is desirable that the apparatus (32) be controlled suchthat the oil sand which passes through the processing zone (68) issubstantially contained in the spiral trough (70) below the height (100)of the spiral trough (70) in order to enhance the processing of the oilsand within the processing zone (68) and to minimize the backflow ofsolid particles towards the first end (42) of the drum (40).

Similarly, it is desirable that the apparatus (32) be controlled suchthat the oil sand or solid stream (36) which passes through thecompressing zone (66) is also substantially contained in the spiraltrough (70) below the height (100) of the spiral trough (72) in order toenhance the compressing or dewatering of the solid stream (36) to expelany water therefrom and to minimize the backflow of solid particlestowards the first end (42) of the drum (40).

Further, it has been found that the feed rate of the oil sand and therotation speed of the drum (40) tend to be related proportionately. Inother words, if the feedrate of the oil sand feed mechanism (73) isincreased, the drum rotational speed is typically increasedproportionately in order to achieve the desired properties of the solidand liquid streams and to permit the apparatus (32) to process the oilsand without any significant back-up of the oil sand in the drum (40).

However, as indicated, as the drum speed increases, the density of thesolid stream (36) at the solid stream outlet (88) will tend to decrease.Conversely, as the drum speed decreases, the density of the solid stream(36) at the solid stream outlet (88) will tend to increase. Thus,although it is desirable to maximize the feedrate of the oil sand feedmechanism (73), a balance is required to be achieved between thefeedrate of the oil sand feed mechanism (73) and the rotation speed ofthe drum (40) in order to achieve the desired density of the solidstream (36).

In operation, the oil sand feedrate sensor (75) and the feedrate sensingstep provide data relating to the actual feedrate of the oil sand feedmechanism (73). The first drum load sensor (60) and the first drum loadsensing step provide data relating to the first drum load exerted on thefirst drum support (52). The second drum load sensor (62) and the seconddrum load sensing step provide data relating to the second drum loadexerted on the second drum support (54).

The controlling step and the controller (126) adjust the rotation of thespeed of the drum (40) and the feedrate of the oil sand feed mechanism(73) in order to maintain a desired or optimum weight distributionbetween the first drum support (52) and the second drum support (54).Thus, the drum rotation speed and the oil sand feedrate are adjusted inresponse to a change in the first drum load and the second drum load.

In this regard, an increase in the first drum load sensed by the firstdrum load sensor (60) is typically indicative of a back-up of the oilsand within the drum (40). Accordingly, the rotation speed of the drum(40) and/or the feedrate of the oil sand feed mechanism (73) may need tobe adjusted to obtain a desired movement or flow of the oil sand and thesolid stream (36) within the drum (40). In particular, the rotationspeed of the drum (40) may be increased and/or the feedrate of the oilsand feed mechanism (73) may be decreased.

A decrease in the second drum load sensed by the second drum load sensor(62) is typically indicative of a decrease in the density of the solidstream (36) at the solid stream outlet (88) below the desired or optimumdensity. Accordingly, the rotation speed of the drum (40) and/or thefeedrate of the oil sand feed mechanism (73) may need to be adjusted toincrease the solid stream density. In particular, the rotation speed ofthe drum (40) may be decreased and/or the feedrate of the oil sand feedmechanism (73) may be increased.

In practice, the desired or optimum density of the solid stream (36) atthe solid stream outlet (88) is predetermined and utilized as a “setpoint” during the operation of the apparatus (32). The “set point” ispredetermined taking into account the desired minimum density of thesolid stream (36) and the desired maximum concentration of the solidparticles in the liquid stream (34). Further, the desired feedrate ofthe oil sand feed mechanism (73) is also selected or predeterminedtaking into account the density set point.

At the commencement of the operation, the rotation speed of the drum(40) is gradually increased to achieve the set point density of thesolid stream (36) at the solid stream outlet (88). Subsequently, duringoperation of the apparatus (32), the rotation speed of the drum (40) maybe adjusted as required in response to a change in one or both of thefirst and second drum loads in order to maintain the density of thesolid stream (36) at the solid stream outlet (88) at the set point.

Finally, in this document, the word “comprising” is used in itsnon-limiting sense to mean that items following the word are included,but items not specifically mentioned are not excluded. A reference to anelement by the indefinite article “a” does not exclude the possibilitythat more than one of the elements is present, unless the contextclearly requires that there be one and only one of the elements.

1. A control system for an apparatus for processing oil sand to producea liquid stream comprising water and bitumen and a solid streamcomprising solid particles, wherein the apparatus is comprised of agenerally cylindrical rotatable drum, a spiral trough extending along aninterior surface of the drum, an oil sand feed mechanism, a drivemechanism for rotating the drum, a first drum support for supporting thedrum, and a second drum support for supporting the drum, wherein thedrum is comprised of a first end, a second end, an oil sand inletlocated adjacent to the first end, and a solid stream outlet locatedadjacent to the second end, wherein the first drum support is locatedbetween the first end of the drum and a midpoint of the drum, andwherein the second drum support is located between the second end of thedrum and the midpoint of the drum, the control system comprising: (a) afirst drum load sensor associated with the first drum support, forsensing a first drum load exerted on the first drum support; (b) asecond drum load sensor associated with the second drum support, forsensing a second drum load exerted on the second drum support; (c) anoil sand feedrate sensor associated with the oil sand feed mechanism,for sensing a feedrate of the oil sand feed mechanism; (d) a controlleroperatively connected with the first drum load sensor, the second drumload sensor, the oil sand feedrate sensor, the drive mechanism and theoil sand feed mechanism, for controlling a rotation speed of the drumand a feedrate of the oil sand feed mechanism in response to input datafrom the first drum load sensor, the second drum load sensor and the oilsand feedrate sensor.
 2. The system as claimed in claim 1 wherein thecontroller is configured so that a density of the solid stream at thesolid stream outlet is maintained at or above a minimum design densityand so that a concentration of the solid particles in the liquid streamis maintained at or below a maximum design concentration.
 3. The systemas claimed in claim 2 wherein the controller is configured to maximizethe feedrate of the oil sand feed mechanism.
 4. The system as claimed inclaim 1 wherein the drum is comprised of a processing zone, wherein thespiral trough extends through the processing zone, wherein the spiraltrough has a height through the processing zone, and wherein thecontroller is configured so that the oil sand which passes through theprocessing zone is substantially contained in the spiral trough belowthe height of the spiral trough.
 5. The system as claimed in claim 4wherein the controller is configured to maximize the feedrate of the oilsand feed mechanism.
 6. The system as claimed in claim 1 wherein thedrum is comprised of a compressing zone, wherein the spiral troughextends through the compressing zone, wherein the spiral trough has aheight through the compressing zone and wherein the controller isconfigured so that the solid stream which passes through the compressingzone is substantially contained in the spiral trough below the height ofthe spiral trough.
 7. The system as claimed in claim 6 wherein thecontroller is configured to maximize the feedrate of the oil sand feedmechanism.
 8. The system as claimed in claim 4 wherein the drum iscomprised of a compressing zone, wherein the spiral trough extendsthrough the compressing zone, wherein the spiral trough has a heightthrough the compressing zone and wherein the controller is configured sothat the solid stream which passes through the compressing zone issubstantially contained in the spiral trough below the height of thespiral trough.
 9. The system as claimed in claim 8 wherein thecontroller is configured to maximize the feedrate of the oil sand feedmechanism.
 10. A method for controlling an apparatus for processing oilsand to produce a liquid stream comprising water and bitumen and a solidstream comprising solid particles, wherein the apparatus is comprised ofa generally cylindrical rotatable drum, a spiral trough extending alongan interior surface of the drum, an oil sand feed mechanism, a drivemechanism for rotating the drum, a first drum support for supporting thedrum, and a second drum support for supporting the drum, wherein thedrum is comprised of a first end, a second end, an oil sand inletlocated adjacent to the first end, and a solid stream outlet locatedadjacent to the second end, wherein the first drum support is locatedbetween the first end of the drum and a midpoint of the drum, andwherein the second drum support is located between the second end of thedrum and the midpoint of the drum, the method comprising: (a) sensing afirst drum load exerted on the first drum support; (b) sensing a seconddrum load exerted on the second drum support; (c) sensing a feedrate ofthe oil sand feed mechanism; and (d) controlling a rotation speed of thedrum and a feedrate of the oil sand feed mechanism in response to inputdata from the first drum load sensing step, the second drum load sensingstep and the feedrate sensing step.
 11. The method as claimed in claim10 wherein the controlling step is performed so that a density of thesolid stream at the solid stream outlet is maintained at or above aminimum design density and so that a concentration of the solidparticles in the liquid stream is maintained at or below a maximumdesign concentration.
 12. The method as claimed in claim 11 wherein thecontrolling step is performed so that the feedrate of the oil sand feedmechanism is maximized.
 13. The method as claimed in claim 10 whereinthe drum is comprised of a processing zone, wherein the spiral troughextends through the processing zone, wherein the spiral trough has aheight through the processing zone, and wherein the controlling step isperformed so that the oil sand which passes through the processing zoneis substantially contained in the spiral trough below the height of thespiral trough.
 14. The method as claimed in claim 13 wherein thecontrolling step is performed so that the feedrate of the oil sand feedmechanism is maximized.
 15. The method as claimed in claim 10 whereinthe drum is comprised of a compressing zone, wherein the spiral troughextends through the compressing zone, wherein the spiral trough has aheight through the compressing zone and wherein the controlling step isperformed so that the solid stream which passes through the compressingzone is substantially contained in the spiral trough below the height ofthe spiral trough.
 16. The method as claimed in claim 15 wherein thecontrolling step is performed so that the feedrate of the oil sand feedmechanism is maximized.
 17. The method as claimed in claim 13 whereinthe drum is comprised of a compressing zone, wherein the spiral troughextends through the compressing zone, wherein the spiral trough has aheight through the compressing zone and wherein the controlling step isperformed so that the solid stream which passes through the compressingzone is substantially contained in the spiral trough below the height ofthe spiral trough.
 18. The method as claimed in claim 17 wherein thecontrolling step is performed so that the feedrate of the oil sand feedmechanism is maximized.